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Date: Thu, 14 May 2020 10:59:31 -0400 From: "Theodore Y. Ts'o" <tytso@....edu> To: Jeffle Xu <jefflexu@...ux.alibaba.com> Cc: jack@...e.cz, linux-ext4@...r.kernel.org, joseph.qi@...ux.alibaba.com Subject: Re: [PATCH v2] ext4: fix error pointer dereference On Thu, Apr 23, 2020 at 03:46:44PM +0800, Jeffle Xu wrote: > Don't pass error pointers to brelse(). > > commit 7159a986b420 ("ext4: fix some error pointer dereferences") has fixed > some cases, fix the remaining one case. > > Once ext4_xattr_block_find()->ext4_sb_bread() failed, error pointer is > stored in @bs->bh, which will be passed to brelse() in the cleanup > routine of ext4_xattr_set_handle(). This will then cause a NULL panic > crash in __brelse(). > > BUG: unable to handle kernel NULL pointer dereference at 000000000000005b > RIP: 0010:__brelse+0x1b/0x50 > Call Trace: > ext4_xattr_set_handle+0x163/0x5d0 > ext4_xattr_set+0x95/0x110 > __vfs_setxattr+0x6b/0x80 > __vfs_setxattr_noperm+0x68/0x1b0 > vfs_setxattr+0xa0/0xb0 > setxattr+0x12c/0x1a0 > path_setxattr+0x8d/0xc0 > __x64_sys_setxattr+0x27/0x30 > do_syscall_64+0x60/0x250 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > In this case, @bs->bh stores '-EIO' actually. > > Fixes: fb265c9cb49e ("ext4: add ext4_sb_bread() to disambiguate ENOMEM cases") > Signed-off-by: Jeffle Xu <jefflexu@...ux.alibaba.com> > Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com> > Cc: stable@...nel.org # 2.6.19 > Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com> > Reviewed-by: Jan Kara <jack@...e.cz> Applied, thanks. - Ted
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