Message-ID: <2131863.1733756813@warthog.procyon.org.uk>
Date: Mon, 09 Dec 2024 15:06:53 +0000
From: David Howells <dhowells@...hat.com>
To: syzbot <syzbot+885c03ad650731743489@...kaller.appspotmail.com>
Cc: dhowells@...hat.com, akpm@...ux-foundation.org,
    asmadeus@...ewreck.org, ericvh@...nel.org,
    linux-kernel@...r.kernel.org, linux-mm@...ck.org,
    linux_oss@...debyte.com, lucho@...kov.net,
    syzkaller-bugs@...glegroups.com, v9fs@...ts.linux.dev
Subject: Re: [syzbot] [mm?] [v9fs?] BUG: stack guard page was hit in sys_open

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

commit 78513c0ee0d9a767b5c2568c6c220a941e73529c
Author: Lizhi Xu <lizhi.xu@...driver.com>
Date:   Fri Nov 8 11:40:20 2024 +0800

    netfs: If didn't read new data then abandon retry
    
    syzkaller reported a three-level circle calls (netfs_rreq_assess,
    netfs_retry_reads, netfs_rreq_terminated), during an unbuffered or direct
    I/O read.  [1]
    
    netfs_rreq_terminated() only checks that subreq's transferred is greater
    than consumed and then sets the retry flag. There is no limit on the number
    of retries, and there is no judgment on whether the retry is effective in
    reading new data. This hitting the stack guard page.
    
    To avoid the issue, let's add retry read times and the length of the data
    just read in struct netfs_io_subrequest, use them to assess the state of a
    read request and decide what to do retry.
    
    [1]
    BUG: TASK stack guard page was hit at ffffc9000482ff48 (stack is ffffc90004830000..ffffc90004838000)
    Oops: stack guard page: 0000 [#1] PREEMPT SMP KASAN NOPTI
    CPU: 3 UID: 0 PID: 6237 Comm: syz-executor663 Not tainted 6.12.0-rc6-syzkaller-00077-g2e1b3cc9d7f7 #0
    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
    RIP: 0010:mark_lock+0x25/0xc60 kernel/locking/lockdep.c:4686
    Code: 90 90 90 90 90 55 48 89 e5 41 57 41 56 41 89 d6 48 ba 00 00 00 00 00 fc ff df 41 55 41 54 53 48 83 e4 f0 48 81 ec 10 01 00 00 <48> c7 44 24 30 b3 8a b5 41 48 8d 44 24 30 48 c7 44 24 38 c0 4d 7a
    RSP: 0018:ffffc9000482ff50 EFLAGS: 00010086
    RAX: 000000000000000c RBX: ffff8880306c2fba RCX: 0000000000000002
    RDX: dffffc0000000000 RSI: ffff8880306c2f98 RDI: ffff8880306c2440
    RBP: ffffc90004830088 R08: 0000000000000000 R09: 0000000000000006
    R10: ffffffff96e2dd27 R11: 0000000000000000 R12: dffffc0000000000
    R13: ffff8880306c2f98 R14: 0000000000000008 R15: ffff8880306c2440
    FS:  00007fedf3b6e6c0(0000) GS:ffff88806a900000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: ffffc9000482ff48 CR3: 000000002c910000 CR4: 0000000000352ef0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     <#DF>
     </#DF>
     <TASK>
     mark_usage kernel/locking/lockdep.c:4646 [inline]
     __lock_acquire+0x906/0x3ce0 kernel/locking/lockdep.c:5156
     lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
     local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
     ___slab_alloc+0x123/0x1880 mm/slub.c:3695
     __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3908
     __slab_alloc_node mm/slub.c:3961 [inline]
     slab_alloc_node mm/slub.c:4122 [inline]
     kmem_cache_alloc_noprof+0x2a7/0x2f0 mm/slub.c:4141
     radix_tree_node_alloc.constprop.0+0x1e8/0x350 lib/radix-tree.c:253
     idr_get_free+0x528/0xa40 lib/radix-tree.c:1506
     idr_alloc_u32+0x191/0x2f0 lib/idr.c:46
     idr_alloc+0xc1/0x130 lib/idr.c:87
     p9_tag_alloc+0x394/0x870 net/9p/client.c:321
     p9_client_prepare_req+0x19f/0x4d0 net/9p/client.c:644
     p9_client_zc_rpc.constprop.0+0x105/0x880 net/9p/client.c:793
     p9_client_read_once+0x443/0x820 net/9p/client.c:1570
     p9_client_read+0x13f/0x1b0 net/9p/client.c:1534
     v9fs_issue_read+0x115/0x310 fs/9p/vfs_addr.c:74
     netfs_retry_read_subrequests fs/netfs/read_retry.c:60 [inline]
     netfs_retry_reads+0x153a/0x1d00 fs/netfs/read_retry.c:232
     netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
     netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
     netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
     netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
     netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
     netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
     netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
     ...
     netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
     netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
     netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
     netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
     netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
     netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
     netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
     netfs_dispatch_unbuffered_reads fs/netfs/direct_read.c:103 [inline]
     netfs_unbuffered_read fs/netfs/direct_read.c:127 [inline]
     netfs_unbuffered_read_iter_locked+0x12f6/0x19b0 fs/netfs/direct_read.c:221
     netfs_unbuffered_read_iter+0xc5/0x100 fs/netfs/direct_read.c:256
     v9fs_file_read_iter+0xbf/0x100 fs/9p/vfs_file.c:361
     do_iter_readv_writev+0x614/0x7f0 fs/read_write.c:832
     vfs_readv+0x4cf/0x890 fs/read_write.c:1025
     do_preadv fs/read_write.c:1142 [inline]
     __do_sys_preadv fs/read_write.c:1192 [inline]
     __se_sys_preadv fs/read_write.c:1187 [inline]
     __x64_sys_preadv+0x22d/0x310 fs/read_write.c:1187
     do_syscall_x64 arch/x86/entry/common.c:52 [inline]
     do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
     entry_SYSCALL_64_after_hwframe+0x77/0x7f
    RIP: 0033:0x7fedf3bd4dd9
    Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
    RSP: 002b:00007fedf3b6e168 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
    RAX: ffffffffffffffda RBX: 00007fedf3c5e318 RCX: 00007fedf3bd4dd9
    RDX: 0000000000000001 RSI: 00000000200015c0 RDI: 0000000000000003
    RBP: 00007fedf3c5e310 R08: 0000000000000000 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000246 R12: 00007fedf3c5e31c
    R13: 000000000000000b R14: 00007fffe9d355b0 R15: 00007fffe9d35698
     </TASK>
    
    Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
    Closes: https://syzkaller.appspot.com/bug?extid=1fc6f64c40a9d143cfb6
    Signed-off-by: David Howells <dhowells@...hat.com>
    Suggested-by: Lizhi Xu <lizhi.xu@...driver.com> [2]
    cc: Dominique Martinet <asmadeus@...ewreck.org>
    cc: Jeff Layton <jlayton@...nel.org>
    cc: v9fs@...ts.linux.dev
    cc: netfs@...ts.linux.dev
    cc: linux-fsdevel@...r.kernel.org
    Link: https://lore.kernel.org/r/20241108034020.3695718-1-lizhi.xu@windriver.com/ [2]

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 819c75233235..3bc9ce6c575e 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -57,6 +57,8 @@ static void v9fs_issue_write(struct netfs_io_subrequest *subreq)
 	int err, len;
 
 	len = p9_client_write(fid, subreq->start, &subreq->io_iter, &err);
+	if (len > 0)
+		__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 	netfs_write_subrequest_terminated(subreq, len ?: err, false);
 }
 
@@ -80,8 +82,10 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
 	if (pos + total >= i_size_read(rreq->inode))
 		__set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags);
 
-	if (!err)
+	if (!err) {
 		subreq->transferred += total;
+		__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
+	}
 
 	netfs_read_subreq_terminated(subreq, err, false);
 }
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 34107b55f834..ccb6aa8027c5 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -122,7 +122,7 @@ static void afs_issue_write_worker(struct work_struct *work)
 	if (subreq->debug_index == 3)
 		return netfs_write_subrequest_terminated(subreq, -ENOANO, false);
 
-	if (!test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) {
+	if (!subreq->retry_count) {
 		set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 		return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
 	}
@@ -149,6 +149,9 @@ static void afs_issue_write_worker(struct work_struct *work)
 	afs_wait_for_operation(op);
 	ret = afs_put_operation(op);
 	switch (ret) {
+	case 0:
+		__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
+		break;
 	case -EACCES:
 	case -EPERM:
 	case -ENOKEY:
diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c
index 46ce3b7adf07..47ed3a5044e2 100644
--- a/fs/netfs/read_collect.c
+++ b/fs/netfs/read_collect.c
@@ -438,7 +438,7 @@ void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq,
 	     rreq->origin == NETFS_READPAGE ||
 	     rreq->origin == NETFS_READ_FOR_WRITE)) {
 		netfs_consume_read_data(subreq, was_async);
-		__clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+		__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 	}
 }
 EXPORT_SYMBOL(netfs_read_subreq_progress);
@@ -497,7 +497,7 @@ void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
 		     rreq->origin == NETFS_READPAGE ||
 		     rreq->origin == NETFS_READ_FOR_WRITE)) {
 			netfs_consume_read_data(subreq, was_async);
-			__clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+			__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 		}
 		rreq->transferred += subreq->transferred;
 	}
@@ -511,10 +511,13 @@ void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
 		} else {
 			trace_netfs_sreq(subreq, netfs_sreq_trace_short);
 			if (subreq->transferred > subreq->consumed) {
-				__set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
-				__clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
-				set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
-			} else if (!__test_and_set_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags)) {
+				/* If we didn't read new data, abandon retry. */
+				if (subreq->retry_count &&
+				    test_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags)) {
+					__set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+					set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
+				}
+			} else if (test_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags)) {
 				__set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 				set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
 			} else {
diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c
index 0350592ea804..0e72e9226fc8 100644
--- a/fs/netfs/read_retry.c
+++ b/fs/netfs/read_retry.c
@@ -56,6 +56,8 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 			if (test_bit(NETFS_SREQ_FAILED, &subreq->flags))
 				break;
 			if (__test_and_clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {
+				__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
+				subreq->retry_count++;
 				netfs_reset_iter(subreq);
 				netfs_reissue_read(rreq, subreq);
 			}
@@ -137,7 +139,8 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 			stream0->sreq_max_len = subreq->len;
 
 			__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
-			__set_bit(NETFS_SREQ_RETRYING, &subreq->flags);
+			__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
+			subreq->retry_count++;
 
 			spin_lock_bh(&rreq->lock);
 			list_add_tail(&subreq->rreq_link, &rreq->subrequests);
@@ -213,7 +216,6 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 			subreq->error = -ENOMEM;
 		__clear_bit(NETFS_SREQ_FAILED, &subreq->flags);
 		__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
-		__clear_bit(NETFS_SREQ_RETRYING, &subreq->flags);
 	}
 	spin_lock_bh(&rreq->lock);
 	list_splice_tail_init(&queue, &rreq->subrequests);
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
index 82290c92ba7a..ca3a11ed9b54 100644
--- a/fs/netfs/write_collect.c
+++ b/fs/netfs/write_collect.c
@@ -179,7 +179,6 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,
 				struct iov_iter source = subreq->io_iter;
 
 				iov_iter_revert(&source, subreq->len - source.count);
-				__set_bit(NETFS_SREQ_RETRYING, &subreq->flags);
 				netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
 				netfs_reissue_write(stream, subreq, &source);
 			}
@@ -234,7 +233,7 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,
 			/* Renegotiate max_len (wsize) */
 			trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
 			__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
-			__set_bit(NETFS_SREQ_RETRYING, &subreq->flags);
+			subreq->retry_count++;
 			stream->prepare_write(subreq);
 
 			part = min(len, stream->sreq_max_len);
@@ -279,7 +278,7 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,
 			subreq->start		= start;
 			subreq->debug_index	= atomic_inc_return(&wreq->subreq_counter);
 			subreq->stream_nr	= to->stream_nr;
-			__set_bit(NETFS_SREQ_RETRYING, &subreq->flags);
+			subreq->retry_count	= 1;
 
 			trace_netfs_sreq_ref(wreq->debug_id, subreq->debug_index,
 					     refcount_read(&subreq->ref),
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index bf6d507578e5..ff0e82505a0b 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -244,6 +244,8 @@ void netfs_reissue_write(struct netfs_io_stream *stream,
 	iov_iter_advance(source, size);
 	iov_iter_truncate(&subreq->io_iter, size);
 
+	subreq->retry_count++;
+	__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 	__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
 	netfs_do_issue_write(stream, subreq);
 }
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index bd42a419458e..6cb1e81993f8 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -1319,14 +1319,16 @@ cifs_readv_callback(struct mid_q_entry *mid)
 	}
 
 	if (rdata->result == -ENODATA) {
-		__set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
 		rdata->result = 0;
+		__set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
 	} else {
 		size_t trans = rdata->subreq.transferred + rdata->got_bytes;
 		if (trans < rdata->subreq.len &&
 		    rdata->subreq.start + trans == ictx->remote_i_size) {
-			__set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
 			rdata->result = 0;
+			__set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
+		} else if (rdata->got_bytes > 0) {
+			__set_bit(NETFS_SREQ_MADE_PROGRESS, &rdata->subreq.flags);
 		}
 	}
 
@@ -1670,10 +1672,13 @@ cifs_writev_callback(struct mid_q_entry *mid)
 		if (written > wdata->subreq.len)
 			written &= 0xFFFF;
 
-		if (written < wdata->subreq.len)
+		if (written < wdata->subreq.len) {
 			result = -ENOSPC;
-		else
+		} else {
 			result = written;
+			if (written > 0)
+				__set_bit(NETFS_SREQ_MADE_PROGRESS, &wdata->subreq.flags);
+		}
 		break;
 	case MID_REQUEST_SUBMITTED:
 	case MID_RETRY_NEEDED:
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 010eae9d6c47..458b53d1f9cb 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -4615,6 +4615,7 @@ smb2_readv_callback(struct mid_q_entry *mid)
 			__set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
 			rdata->result = 0;
 		}
+		__set_bit(NETFS_SREQ_MADE_PROGRESS, &rdata->subreq.flags);
 	}
 	trace_smb3_rw_credits(rreq_debug_id, subreq_debug_index, rdata->credits.value,
 			      server->credits, server->in_flight,
@@ -4840,10 +4841,12 @@ smb2_writev_callback(struct mid_q_entry *mid)
 		if (written > wdata->subreq.len)
 			written &= 0xFFFF;
 
-		if (written < wdata->subreq.len)
+		if (written < wdata->subreq.len) {
 			wdata->result = -ENOSPC;
-		else
+		} else if (written > 0) {
 			wdata->subreq.len = written;
+			__set_bit(NETFS_SREQ_MADE_PROGRESS, &wdata->subreq.flags);
+		}
 		break;
 	case MID_REQUEST_SUBMITTED:
 	case MID_RETRY_NEEDED:
@@ -5012,7 +5015,7 @@ smb2_async_writev(struct cifs_io_subrequest *wdata)
 	}
 #endif
 
-	if (test_bit(NETFS_SREQ_RETRYING, &wdata->subreq.flags))
+	if (wdata->subreq.retry_count > 0)
 		smb2_set_replay(server, &rqst);
 
 	cifs_dbg(FYI, "async write at %llu %u bytes iter=%zx\n",
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 5eaceef41e6c..4083d77e3f39 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -185,6 +185,7 @@ struct netfs_io_subrequest {
 	short			error;		/* 0 or error that occurred */
 	unsigned short		debug_index;	/* Index in list (for debugging output) */
 	unsigned int		nr_segs;	/* Number of segs in io_iter */
+	u8			retry_count;	/* The number of retries (0 on initial pass) */
 	enum netfs_io_source	source;		/* Where to read from/write to */
 	unsigned char		stream_nr;	/* I/O stream this belongs to */
 	unsigned char		curr_folioq_slot; /* Folio currently being read */
@@ -194,14 +195,13 @@ struct netfs_io_subrequest {
 #define NETFS_SREQ_COPY_TO_CACHE	0	/* Set if should copy the data to the cache */
 #define NETFS_SREQ_CLEAR_TAIL		1	/* Set if the rest of the read should be cleared */
 #define NETFS_SREQ_SEEK_DATA_READ	3	/* Set if ->read() should SEEK_DATA first */
-#define NETFS_SREQ_NO_PROGRESS		4	/* Set if we didn't manage to read any data */
+#define NETFS_SREQ_MADE_PROGRESS	4	/* Set if we transferred at least some data */
 #define NETFS_SREQ_ONDEMAND		5	/* Set if it's from on-demand read mode */
 #define NETFS_SREQ_BOUNDARY		6	/* Set if ends on hard boundary (eg. ceph object) */
 #define NETFS_SREQ_HIT_EOF		7	/* Set if short due to EOF */
 #define NETFS_SREQ_IN_PROGRESS		8	/* Unlocked when the subrequest completes */
 #define NETFS_SREQ_NEED_RETRY		9	/* Set if the filesystem requests a retry */
-#define NETFS_SREQ_RETRYING		10	/* Set if we're retrying */
-#define NETFS_SREQ_FAILED		11	/* Set if the subreq failed unretryably */
+#define NETFS_SREQ_FAILED		10	/* Set if the subreq failed unretryably */
 };
 
 enum netfs_io_origin {

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