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Date: Mon, 1 Jul 2024 22:36:06 +0800
From: Baokun Li <libaokun1@...wei.com>
To: syzbot <syzbot+ae688d469e36fb5138d0@...kaller.appspotmail.com>,
<adilger.kernel@...ger.ca>, <linux-ext4@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <syzkaller-bugs@...glegroups.com>,
<tytso@....edu>
Subject: Re: [syzbot] [ext4?] BUG: unable to handle kernel paging request in
do_split
On 2024/6/29 18:05, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 55027e689933 Merge tag 'input-for-v6.10-rc5' of git://git...
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=100ec271980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=67463c0717b8d4ca
> dashboard link: https://syzkaller.appspot.com/bug?extid=ae688d469e36fb5138d0
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14296bb6980000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10a53e3e980000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/5a4561e75890/disk-55027e68.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/40e478722974/vmlinux-55027e68.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/d3bbbd2462f2/bzImage-55027e68.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/451986899a3c/mount_0.gz
>
> Bisection is inconclusive: the first bad commit could be any of:
>
> 3b51788a2d5f IB/hfi1: use new function dev_fetch_sw_netstats
> 44fa32f008ab net: add function dev_fetch_sw_netstats for fetching pcpu_sw_netstats
> 3618ad2a7c0e virtio-net: ethtool configurable RXCSUM
> 9d0151673e70 net: macsec: use new function dev_fetch_sw_netstats
> c9bf52a173c7 net/af_unix: Remove unused old_pid variable
> ec173778e96e net: usb: qmi_wwan: use new function dev_fetch_sw_netstats
> 0403a2b53c29 net/tls: use semicolons rather than commas to separate statements
> ab2b3ff21b9f net: usbnet: use new function dev_fetch_sw_netstats
> 1f68b2096f65 qtnfmac: use new function dev_fetch_sw_netstats
> 6159e9633f17 net/ipv6: use semicolons rather than commas to separate statements
> 44797589c20e tcp: use semicolons rather than commas to separate statements
> f3f04f0f3ab9 net: bridge: use new function dev_fetch_sw_netstats
> 7e38b03f0fe7 net: mscc: ocelot: remove duplicate ocelot_port_dev_check
> a0d269810185 net: dsa: use new function dev_fetch_sw_netstats
> c93c5482c7d4 Merge branch 'macb-support-the-2-deep-Tx-queue-on-at91'
> cf89f18fa407 iptunnel: use new function dev_fetch_sw_netstats
> 0a4e9ce17ba7 macb: support the two tx descriptors on at91rm9200
> 6401297e7610 mac80211: use new function dev_fetch_sw_netstats
> 3569939a811e net: openvswitch: use new function dev_fetch_sw_netstats
> 73d742281383 macb: prepare at91 to use a 2-frame TX queue
> 5fc3594d36d1 xfrm: use new function dev_fetch_sw_netstats
> fa6031df12fc macb: add RM9200's interrupt flag TBRE
> a003ec1f47bc Merge branch 'net-add-and-use-function-dev_fetch_sw_netstats-for-fetching-pcpu_sw_netstats'
> ccdf7fae3afa Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
> 30cf856a691f i40e: Allow changing FEC settings on X722 if supported by FW
> a308283fdbf7 Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next
> 793d5d612426 netfilter: flowtable: reduce calls to pskb_may_pull()
> f2bf814a27c5 e1000: remove unused and incorrect code
> d3519cb89f6d netfilter: nf_tables: add inet ingress support
> d5e6f064ac66 Merge branch '40GbE-Intel-Wired-LAN-Driver-Updates-2020-10-12'
> 50172733d01c Merge tag 'mlx5-updates-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux
> 60a3815da702 netfilter: add inet ingress support
> d25e2e9388ed netfilter: restore NF_INET_NUMHOOKS
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14154fda980000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+ae688d469e36fb5138d0@...kaller.appspotmail.com
>
> EXT4-fs error (device loop0): ext4_orphan_get:1399: comm syz-executor306: couldn't read orphan inode 15 (err -117)
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
> BUG: unable to handle page fault for address: ffffed11022e24fe
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 23ffee067 P4D 23ffee067 PUD 0
> Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI
> CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-syzkaller-00018-g55027e689933 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
> RIP: 0010:do_split+0x150b/0x2490 fs/ext4/namei.c:2046
> Code: 89 f8 48 c1 e8 03 0f b6 04 10 84 c0 48 89 74 24 18 0f 85 f5 0c 00 00 46 8b 3c f6 41 8d 46 ff 48 8d 1c c6 48 89 d8 48 c1 e8 03 <0f> b6 04 10 84 c0 4c 8b a4 24 98 00 00 00 0f 85 f7 0c 00 00 8b 1b
> RSP: 0018:ffffc9000327f060 EFLAGS: 00010a02
> RAX: 1ffff111022e24fe RBX: ffff8888117127f0 RCX: ffff8880237e1e00
> RDX: dffffc0000000000 RSI: ffff8880117127f8 RDI: ffff8880117127f8
> RBP: ffffc9000327f250 R08: ffffffff825fc2ad R09: ffffffff82541cf8
> R10: 0000000000000007 R11: ffffffff825435f0 R12: 0000000000000000
> R13: 0000000000000400 R14: 0000000000000000 R15: 000000002b74e18c
> FS: 00005555787b4380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffed11022e24fe CR3: 0000000043598000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341
> ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451
> ext4_rename fs/ext4/namei.c:3936 [inline]
> ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214
> vfs_rename+0xbdb/0xf00 fs/namei.c:4887
> do_renameat2+0xd94/0x13f0 fs/namei.c:5044
> __do_sys_rename fs/namei.c:5091 [inline]
> __se_sys_rename fs/namei.c:5089 [inline]
> __x64_sys_rename+0x86/0xa0 fs/namei.c:5089
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fe5c7dcdb59
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffcd201c228 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
> RAX: ffffffffffffffda RBX: 00007fe5c7e16568 RCX: 00007fe5c7dcdb59
> RDX: 0000000000000000 RSI: 0000000020000f40 RDI: 00000000200003c0
> RBP: 00007fe5c7e16668 R08: 00005555787b54c0 R09: 00005555787b54c0
> R10: 00005555787b54c0 R11: 0000000000000246 R12: 00007ffcd201c250
> R13: 00007ffcd201c478 R14: 431bde82d7b634db R15: 00007fe5c7e1603b
> </TASK>
> Modules linked in:
> CR2: ffffed11022e24fe
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:do_split+0x150b/0x2490 fs/ext4/namei.c:2046
> Code: 89 f8 48 c1 e8 03 0f b6 04 10 84 c0 48 89 74 24 18 0f 85 f5 0c 00 00 46 8b 3c f6 41 8d 46 ff 48 8d 1c c6 48 89 d8 48 c1 e8 03 <0f> b6 04 10 84 c0 4c 8b a4 24 98 00 00 00 0f 85 f7 0c 00 00 8b 1b
> RSP: 0018:ffffc9000327f060 EFLAGS: 00010a02
> RAX: 1ffff111022e24fe RBX: ffff8888117127f0 RCX: ffff8880237e1e00
> RDX: dffffc0000000000 RSI: ffff8880117127f8 RDI: ffff8880117127f8
> RBP: ffffc9000327f250 R08: ffffffff825fc2ad R09: ffffffff82541cf8
> R10: 0000000000000007 R11: ffffffff825435f0 R12: 0000000000000000
> R13: 0000000000000400 R14: 0000000000000000 R15: 000000002b74e18c
> FS: 00005555787b4380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffed11022e24fe CR3: 0000000043598000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
> 0: 89 f8 mov %edi,%eax
> 2: 48 c1 e8 03 shr $0x3,%rax
> 6: 0f b6 04 10 movzbl (%rax,%rdx,1),%eax
> a: 84 c0 test %al,%al
> c: 48 89 74 24 18 mov %rsi,0x18(%rsp)
> 11: 0f 85 f5 0c 00 00 jne 0xd0c
> 17: 46 8b 3c f6 mov (%rsi,%r14,8),%r15d
> 1b: 41 8d 46 ff lea -0x1(%r14),%eax
> 1f: 48 8d 1c c6 lea (%rsi,%rax,8),%rbx
> 23: 48 89 d8 mov %rbx,%rax
> 26: 48 c1 e8 03 shr $0x3,%rax
> * 2a: 0f b6 04 10 movzbl (%rax,%rdx,1),%eax <-- trapping instruction
> 2e: 84 c0 test %al,%al
> 30: 4c 8b a4 24 98 00 00 mov 0x98(%rsp),%r12
> 37: 00
> 38: 0f 85 f7 0c 00 00 jne 0xd35
> 3e: 8b 1b mov (%rbx),%ebx
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
The immediate cause of this problem is that there is only one valid
dentry for the block to be split during do_split, so split==0 results
in out-of-bounds accesses to the map triggering the problem.
do_split
unsigned split
dx_make_map
count = 1
split = count/2 = 0;
continued = hash2 == map[split - 1].hash;
---> map[4294967295]
The root cause is that syzbot constructs a directory that is not inline
but does not have a dirblock, and we don't check for it when we create
files under the folder.
ext4_mknod
ext4_add_entry
// Read block 0
ext4_read_dirblock(dir, block, DIRENT)
bh = ext4_bread(NULL, inode, block, 0)
if (!bh && (type == INDEX || type == DIRENT_HTREE))
// The first directory block is a hole
// But type == DIRENT, so no error is reported.
Therefore, reporting error when ext4_read_dirblock() finds the first
directory block is a hole to avoid error spreading leading to
something bad.
Here's the patch in testing, I'll send it out officially after it is
tested.
Regards,
Baokun
From: Baokun Li <libaokun1@...wei.com>
Date: Mon, 1 Jul 2024 20:23:59 +0800
Subject: [PATCH] ext4: make sure the first directory block is not a hole
Syzbot reports a issue as follows:
============================================
BUG: unable to handle page fault for address: ffffed11022e24fe
PGD 23ffee067 P4D 23ffee067 PUD 0
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted
6.10.0-rc5-g55027e689933 #0
Call Trace:
<TASK>
make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341
ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451
ext4_rename fs/ext4/namei.c:3936 [inline]
ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214
[...]
============================================
The immediate cause of this problem is that there is only one valid
dentry for
the block to be split during do_split, so split==0 results in out-of-bounds
accesses to the map triggering the problem.
do_split
unsigned split
dx_make_map
count = 1
split = count/2 = 0;
continued = hash2 == map[split - 1].hash;
---> map[4294967295]
The root cause is that the syzbot constructs a directory that is not
inline but
does not have a dirblock, and we don't check for it when we create files
under
the folder.
ext4_mknod
ext4_add_entry
// Read block 0
ext4_read_dirblock(dir, block, DIRENT)
bh = ext4_bread(NULL, inode, block, 0)
if (!bh && (type == INDEX || type == DIRENT_HTREE))
// The first directory block is a hole
// But type == DIRENT, so no error is reported.
Therefore, report that the filesystem is corrupted when ext4_read_dirblock()
finds the first directory block to be a hole, to avoid spreading the
error to
cause something bad.
Fixes: 4e19d6b65fb4 ("ext4: allow directory holes")
Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
fs/ext4/namei.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index a630b27a4cc6..facdf0e97a48 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -151,7 +151,8 @@ static struct buffer_head
*__ext4_read_dirblock(struct inode *inode,
return bh;
}
- if (!bh && (type == INDEX || type == DIRENT_HTREE)) {
+ /* The first directory block must not be a hole. */
+ if (!bh && (type == INDEX || type == DIRENT_HTREE || block == 0)) {
ext4_error_inode(inode, func, line, block,
"Directory hole found for htree %s block",
(type == INDEX) ? "index" : "leaf");
@@ -3083,10 +3084,7 @@ bool ext4_empty_dir(struct inode *inode)
EXT4_ERROR_INODE(inode, "invalid size");
return false;
}
- /* The first directory block must not be a hole,
- * so treat it as DIRENT_HTREE
- */
- bh = ext4_read_dirblock(inode, 0, DIRENT_HTREE);
+ bh = ext4_read_dirblock(inode, 0, EITHER)
if (IS_ERR(bh))
return false;
@@ -3531,10 +3529,7 @@ static struct buffer_head
*ext4_get_first_dir_block(handle_t *handle,
struct ext4_dir_entry_2 *de;
unsigned int offset;
- /* The first directory block must not be a hole, so
- * treat it as DIRENT_HTREE
- */
- bh = ext4_read_dirblock(inode, 0, DIRENT_HTREE);
+ bh = ext4_read_dirblock(inode, 0, EITHER);
if (IS_ERR(bh)) {
*retval = PTR_ERR(bh);
return NULL;
--
2.31.1
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