Message-ID: <348740ed-afea-4c6d-9326-819c8c416676@oracle.com>
Date: Wed, 4 Sep 2024 10:35:34 -0500
From: Dave Kleikamp <dave.kleikamp@...cle.com>
To: Zhao Mengmeng <zhaomengmeng@...inos.cn>, walmeida@...rosoft.com,
        llfamsec@...il.com, brauner@...nel.org, gregkh@...uxfoundation.org,
        zhaomzhao@....com
Cc: jfs-discussion@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        syzbot+02341e0daa42a15ce130@...kaller.appspotmail.com
Subject: Re: [PATCH v1] jfs: Fix uninit-value access of new_ea in ea_buffer

On 9/3/24 8:07PM, Zhao Mengmeng wrote:
> syzbot reports that lzo1x_1_do_compress is using uninit-value:

Looks good. I'm trimming down the commit header since the stack traces 
aren't very useful.

I think the important fields are all set correctly when necessary, but 
the structure does contain some reserved bytes as padding, so the 
initialization is good to have.

Applied.

Shaggy
> 
> =====================================================
> BUG: KMSAN: uninit-value in lzo1x_1_do_compress+0x19f9/0x2510 lib/lzo/lzo1x_compress.c:178
>   lzo1x_1_do_compress+0x19f9/0x2510 lib/lzo/lzo1x_compress.c:178
>   lzogeneric1x_1_compress+0x26a/0x11b0 lib/lzo/lzo1x_compress.c:333
>   lzo1x_1_compress+0x47/0x80 lib/lzo/lzo1x_compress.c:383
>   __lzo_compress crypto/lzo.c:58 [inline]
>   lzo_scompress+0x98/0x180 crypto/lzo.c:79
>   scomp_acomp_comp_decomp+0x7c6/0xb90
>   scomp_acomp_compress+0x32/0x40 crypto/scompress.c:187
>   crypto_acomp_compress include/crypto/acompress.h:251 [inline]
>   zswap_compress+0x368/0xad0 mm/zswap.c:927
>   zswap_store+0x1af3/0x2dd0 mm/zswap.c:1459
>   swap_writepage+0x11f/0x470 mm/page_io.c:198
>   shmem_writepage+0x1a75/0x1f70 mm/shmem.c:1536
>   pageout mm/vmscan.c:680 [inline]
>   shrink_folio_list+0x577f/0x7cb0 mm/vmscan.c:1360
>   evict_folios+0x9bce/0xbc80 mm/vmscan.c:4580
>   try_to_shrink_lruvec+0x13a3/0x1750 mm/vmscan.c:4775
>   shrink_one+0x646/0xd20 mm/vmscan.c:4813
>   shrink_many mm/vmscan.c:4876 [inline]
>   lru_gen_shrink_node mm/vmscan.c:4954 [inline]
>   shrink_node+0x451a/0x50f0 mm/vmscan.c:5934
>   kswapd_shrink_node mm/vmscan.c:6762 [inline]
>   balance_pgdat mm/vmscan.c:6954 [inline]
>   kswapd+0x257e/0x4290 mm/vmscan.c:7223
>   kthread+0x3dd/0x540 kernel/kthread.c:389
>   ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> 
> Uninit was stored to memory at:
>   memcpy_from_iter lib/iov_iter.c:73 [inline]
>   iterate_bvec include/linux/iov_iter.h:122 [inline]
>   iterate_and_advance2 include/linux/iov_iter.h:249 [inline]
>   iterate_and_advance include/linux/iov_iter.h:271 [inline]
>   __copy_from_iter lib/iov_iter.c:249 [inline]
>   copy_page_from_iter_atomic+0x12bb/0x2ae0 lib/iov_iter.c:481
>   copy_folio_from_iter_atomic include/linux/uio.h:186 [inline]
>   generic_perform_write+0x896/0x12e0 mm/filemap.c:4032
>   shmem_file_write_iter+0x2bd/0x2f0 mm/shmem.c:3074
>   do_iter_readv_writev+0x8a1/0xa40
>   vfs_iter_write+0x459/0xd50 fs/read_write.c:895
>   lo_write_bvec drivers/block/loop.c:243 [inline]
>   lo_write_simple drivers/block/loop.c:264 [inline]
>   do_req_filebacked drivers/block/loop.c:511 [inline]
>   loop_handle_cmd drivers/block/loop.c:1910 [inline]
>   loop_process_work+0x15ec/0x3750 drivers/block/loop.c:1945
>   loop_rootcg_workfn+0x2b/0x40 drivers/block/loop.c:1976
>   process_one_work kernel/workqueue.c:3231 [inline]
>   process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3312
>   worker_thread+0xea7/0x14d0 kernel/workqueue.c:3389
>   kthread+0x3dd/0x540 kernel/kthread.c:389
>   ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> 
> Uninit was stored to memory at:
>   copy_to_dinode+0x881/0xb30 fs/jfs/jfs_imap.c:3158
>   diWrite+0x1bf5/0x1f00 fs/jfs/jfs_imap.c:790
>   txCommit+0xdb8/0x8cd0 fs/jfs/jfs_txnmgr.c:1255
>   __jfs_xattr_set+0x1b7/0x1f0 fs/jfs/xattr.c:936
>   jfs_xattr_set+0x79/0x90 fs/jfs/xattr.c:958
>   __vfs_setxattr+0x844/0x8b0 fs/xattr.c:200
>   __vfs_setxattr_noperm+0x22f/0xb00 fs/xattr.c:234
>   __vfs_setxattr_locked+0x441/0x480 fs/xattr.c:295
>   vfs_setxattr+0x294/0x650 fs/xattr.c:321
>   do_setxattr fs/xattr.c:629 [inline]
>   __do_sys_fsetxattr fs/xattr.c:710 [inline]
>   __se_sys_fsetxattr+0x7f0/0x980 fs/xattr.c:686
>   __x64_sys_fsetxattr+0xe4/0x150 fs/xattr.c:686
>   x64_sys_call+0x19c3/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:191
>   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>   do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
>   entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> Uninit was stored to memory at:
>   ea_put fs/jfs/xattr.c:639 [inline]
>   __jfs_setxattr+0x185f/0x1ae0 fs/jfs/xattr.c:785
>   __jfs_xattr_set+0xe6/0x1f0 fs/jfs/xattr.c:934
>   jfs_xattr_set+0x79/0x90 fs/jfs/xattr.c:958
>   __vfs_setxattr+0x844/0x8b0 fs/xattr.c:200
>   __vfs_setxattr_noperm+0x22f/0xb00 fs/xattr.c:234
>   __vfs_setxattr_locked+0x441/0x480 fs/xattr.c:295
>   vfs_setxattr+0x294/0x650 fs/xattr.c:321
>   do_setxattr fs/xattr.c:629 [inline]
>   __do_sys_fsetxattr fs/xattr.c:710 [inline]
>   __se_sys_fsetxattr+0x7f0/0x980 fs/xattr.c:686
>   __x64_sys_fsetxattr+0xe4/0x150 fs/xattr.c:686
>   x64_sys_call+0x19c3/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:191
>   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>   do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
>   entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> Local variable ea_buf created at:
>   __jfs_setxattr+0x5d/0x1ae0 fs/jfs/xattr.c:662
>   __jfs_xattr_set+0xe6/0x1f0 fs/jfs/xattr.c:934
> 
> CPU: 0 UID: 0 PID: 81 Comm: kswapd0 Tainted: G        W          6.11.0-rc5-syzkaller #0
> Tainted: [W]=WARN
> =====================================================
> 
> The reason is ea_buf->new_ea is not initialized properly.
> 
> Fix this by using memset to empty its content at the beginning
> in ea_get().
> 
> Reported-by: syzbot+02341e0daa42a15ce130@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=02341e0daa42a15ce130
> Signed-off-by: Zhao Mengmeng <zhaomengmeng@...inos.cn>
> ---
>   fs/jfs/xattr.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/fs/jfs/xattr.c b/fs/jfs/xattr.c
> index 2999ed5d83f5..0fb05e314edf 100644
> --- a/fs/jfs/xattr.c
> +++ b/fs/jfs/xattr.c
> @@ -434,6 +434,8 @@ static int ea_get(struct inode *inode, struct ea_buffer *ea_buf, int min_size)
>   	int rc;
>   	int quota_allocation = 0;
>   
> +	memset(&ea_buf->new_ea, 0, sizeof(ea_buf->new_ea));
> +
>   	/* When fsck.jfs clears a bad ea, it doesn't clear the size */
>   	if (ji->ea.flag == 0)
>   		ea_size = 0;

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