| Message ID | 1587626854-73470-1-git-send-email-jefflexu@linux.alibaba.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ext4: fix error pointer dereference | expand |
Please ignore this patch since there's a bug in this patch. Sorry for that. On 4/23/20 3:27 PM, 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@linux.alibaba.com> > Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> > Cc: stable@kernel.org # 2.6.19 > --- > fs/ext4/xattr.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c > index 21df43a..c0ebd0f 100644 > --- a/fs/ext4/xattr.c > +++ b/fs/ext4/xattr.c > @@ -1800,8 +1800,10 @@ struct ext4_xattr_block_find { > if (EXT4_I(inode)->i_file_acl) { > /* The inode already has an extended attribute block. */ > bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO); > - if (IS_ERR(bs->bh)) > + if (IS_ERR(bs->bh)) { > + bs->bh = NULL; > return PTR_ERR(bs->bh); > + } > ea_bdebug(bs->bh, "b_count=%d, refcount=%d", > atomic_read(&(bs->bh->b_count)), > le32_to_cpu(BHDR(bs->bh)->h_refcount));
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 21df43a..c0ebd0f 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1800,8 +1800,10 @@ struct ext4_xattr_block_find { if (EXT4_I(inode)->i_file_acl) { /* The inode already has an extended attribute block. */ bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO); - if (IS_ERR(bs->bh)) + if (IS_ERR(bs->bh)) { + bs->bh = NULL; return PTR_ERR(bs->bh); + } ea_bdebug(bs->bh, "b_count=%d, refcount=%d", atomic_read(&(bs->bh->b_count)), le32_to_cpu(BHDR(bs->bh)->h_refcount));
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@linux.alibaba.com> Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: stable@kernel.org # 2.6.19 --- fs/ext4/xattr.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)