ext4: fix error pointer dereference
commit8418897f1b
upstream. Don't pass error pointers to brelse(). commit7159a986b4
("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:fb265c9cb4
("ext4: add ext4_sb_bread() to disambiguate ENOMEM cases") Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com> Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: stable@kernel.org # 2.6.19 Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/1587628004-95123-1-git-send-email-jefflexu@linux.alibaba.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1820,8 +1820,11 @@ ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
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if (EXT4_I(inode)->i_file_acl) {
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/* The inode already has an extended attribute block. */
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bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
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if (IS_ERR(bs->bh))
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return PTR_ERR(bs->bh);
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if (IS_ERR(bs->bh)) {
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error = PTR_ERR(bs->bh);
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bs->bh = NULL;
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return error;
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}
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ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
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atomic_read(&(bs->bh->b_count)),
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le32_to_cpu(BHDR(bs->bh)->h_refcount));
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