* Re: [PATCH] ocfs2: Fix use-after-free in ocfs2_dx_dir_lookup_rec
2025-10-05 15:14 [PATCH] ocfs2: Fix use-after-free in ocfs2_dx_dir_lookup_rec ssrane_b23
@ 2025-10-09 1:29 ` Joseph Qi
2025-10-10 0:52 ` kernel test robot
1 sibling, 0 replies; 3+ messages in thread
From: Joseph Qi @ 2025-10-09 1:29 UTC (permalink / raw)
To: ssrane_b23, Mark Fasheh
Cc: Joel Becker, ocfs2-devel, linux-kernel,
syzbot+30b53487d00b4f7f0922
Hi,
This seems to be fixed by the following commit:
44acc46d182f ocfs2: avoid NULL pointer dereference in dx_dir_lookup_rec()
Thanks,
Joseph
On 2025/10/5 23:14, ssrane_b23@ee.vjti.ac.in wrote:
> From: Shaurya Rane <ssrane_b23@ee.vjti.ac.in>
>
> A syzbot report triggered a KASAN use-after-free read when creating a
> file on a corrupted OCFS2 filesystem image.
>
> The crash occurs in an error-handling path within the
> ocfs2_dx_dir_lookup_rec function. When the function fails to find a
> matching extent record (`found` is false), it attempts to log details
> about the corruption by reading from the `rec` variable.
>
> According to the KASAN report, the memory pointed to by `rec` can be
> invalid at this point, leading to a kernel crash.
>
> Fix this by modifying the error message to use only variables that are
> known to be safe, such as the inode number and the extent block's
> buffer head block number. This preserves the valuable error log for
> debugging corrupted filesystems while preventing the memory safety
> violation.
>
> Reported-by: syzbot+30b53487d00b4f7f0922@syzkaller.appspotmail.com
> Tested-by: syzbot+30b53487d00b4f7f0922@syzkaller.appspotmail.com
> Signed-off-by: Shaurya Rane <ssrane_b23@ee.vjti.ac.in>
> ---
> fs/ocfs2/dir.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
> index 8c9c4825f984..8c4dd61efa8d 100644
> --- a/fs/ocfs2/dir.c
> +++ b/fs/ocfs2/dir.c
> @@ -820,8 +820,7 @@ static int ocfs2_dx_dir_lookup_rec(struct inode *inode,
> ret = ocfs2_error(inode->i_sb,
> "Inode %lu has bad extent record (%u, %u, 0) in btree\n",
> inode->i_ino,
> - le32_to_cpu(rec->e_cpos),
> - ocfs2_rec_clusters(el, rec));
> + eb_bh ? (unsigned long long)eb_bh->b_blocknr : 0);
> goto out;
> }
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ocfs2: Fix use-after-free in ocfs2_dx_dir_lookup_rec
2025-10-05 15:14 [PATCH] ocfs2: Fix use-after-free in ocfs2_dx_dir_lookup_rec ssrane_b23
2025-10-09 1:29 ` Joseph Qi
@ 2025-10-10 0:52 ` kernel test robot
1 sibling, 0 replies; 3+ messages in thread
From: kernel test robot @ 2025-10-10 0:52 UTC (permalink / raw)
To: ssrane_b23, Mark Fasheh
Cc: oe-kbuild-all, Joel Becker, Joseph Qi, ocfs2-devel, linux-kernel,
syzbot+30b53487d00b4f7f0922, Shaurya Rane
Hi,
kernel test robot noticed the following build warnings:
[auto build test WARNING on brauner-vfs/vfs.all]
[also build test WARNING on linus/master v6.17 next-20251009]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/ssrane_b23-ee-vjti-ac-in/ocfs2-Fix-use-after-free-in-ocfs2_dx_dir_lookup_rec/20251009-163456
base: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link: https://lore.kernel.org/r/20251005151403.9012-1-ssranevjti%40gmail.com
patch subject: [PATCH] ocfs2: Fix use-after-free in ocfs2_dx_dir_lookup_rec
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20251010/202510100838.uqgonWvJ-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251010/202510100838.uqgonWvJ-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510100838.uqgonWvJ-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from fs/ocfs2/dir.c:45:
fs/ocfs2/dir.c: In function 'ocfs2_dx_dir_lookup_rec':
>> fs/ocfs2/dir.c:821:35: warning: format '%u' expects argument of type 'unsigned int', but argument 5 has type 'long long unsigned int' [-Wformat=]
821 | "Inode %lu has bad extent record (%u, %u, 0) in btree\n",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
822 | inode->i_ino,
823 | eb_bh ? (unsigned long long)eb_bh->b_blocknr : 0);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| long long unsigned int
fs/ocfs2/super.h:18:48: note: in definition of macro 'ocfs2_error'
18 | __ocfs2_error(sb, __PRETTY_FUNCTION__, fmt, ##__VA_ARGS__)
| ^~~
fs/ocfs2/dir.c:821:70: note: format string is defined here
821 | "Inode %lu has bad extent record (%u, %u, 0) in btree\n",
| ~^
| |
| unsigned int
| %llu
>> fs/ocfs2/dir.c:821:35: warning: format '%u' expects a matching 'unsigned int' argument [-Wformat=]
821 | "Inode %lu has bad extent record (%u, %u, 0) in btree\n",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/ocfs2/super.h:18:48: note: in definition of macro 'ocfs2_error'
18 | __ocfs2_error(sb, __PRETTY_FUNCTION__, fmt, ##__VA_ARGS__)
| ^~~
fs/ocfs2/dir.c:821:74: note: format string is defined here
821 | "Inode %lu has bad extent record (%u, %u, 0) in btree\n",
| ~^
| |
| unsigned int
vim +821 fs/ocfs2/dir.c
316f4b9f98a353a Mark Fasheh 2007-09-07 768
9b7895efac906d6 Mark Fasheh 2008-11-12 769 static int ocfs2_dx_dir_lookup_rec(struct inode *inode,
9b7895efac906d6 Mark Fasheh 2008-11-12 770 struct ocfs2_extent_list *el,
9b7895efac906d6 Mark Fasheh 2008-11-12 771 u32 major_hash,
9b7895efac906d6 Mark Fasheh 2008-11-12 772 u32 *ret_cpos,
9b7895efac906d6 Mark Fasheh 2008-11-12 773 u64 *ret_phys_blkno,
9b7895efac906d6 Mark Fasheh 2008-11-12 774 unsigned int *ret_clen)
23193e513d1cd69 Mark Fasheh 2007-09-12 775 {
9b7895efac906d6 Mark Fasheh 2008-11-12 776 int ret = 0, i, found;
9b7895efac906d6 Mark Fasheh 2008-11-12 777 struct buffer_head *eb_bh = NULL;
9b7895efac906d6 Mark Fasheh 2008-11-12 778 struct ocfs2_extent_block *eb;
9b7895efac906d6 Mark Fasheh 2008-11-12 779 struct ocfs2_extent_rec *rec = NULL;
23193e513d1cd69 Mark Fasheh 2007-09-12 780
9b7895efac906d6 Mark Fasheh 2008-11-12 781 if (el->l_tree_depth) {
facdb77f54f09a3 Joel Becker 2009-02-12 782 ret = ocfs2_find_leaf(INODE_CACHE(inode), el, major_hash,
facdb77f54f09a3 Joel Becker 2009-02-12 783 &eb_bh);
9b7895efac906d6 Mark Fasheh 2008-11-12 784 if (ret) {
9b7895efac906d6 Mark Fasheh 2008-11-12 785 mlog_errno(ret);
9b7895efac906d6 Mark Fasheh 2008-11-12 786 goto out;
9b7895efac906d6 Mark Fasheh 2008-11-12 787 }
23193e513d1cd69 Mark Fasheh 2007-09-12 788
9b7895efac906d6 Mark Fasheh 2008-11-12 789 eb = (struct ocfs2_extent_block *) eb_bh->b_data;
9b7895efac906d6 Mark Fasheh 2008-11-12 790 el = &eb->h_list;
4a12ca3a00a244e Mark Fasheh 2008-11-12 791
9b7895efac906d6 Mark Fasheh 2008-11-12 792 if (el->l_tree_depth) {
17a5b9ab32fe046 Goldwyn Rodrigues 2015-09-04 793 ret = ocfs2_error(inode->i_sb,
7ecef14ab1db961 Joe Perches 2015-09-04 794 "Inode %lu has non zero tree depth in btree tree block %llu\n",
7ecef14ab1db961 Joe Perches 2015-09-04 795 inode->i_ino,
9b7895efac906d6 Mark Fasheh 2008-11-12 796 (unsigned long long)eb_bh->b_blocknr);
9b7895efac906d6 Mark Fasheh 2008-11-12 797 goto out;
9b7895efac906d6 Mark Fasheh 2008-11-12 798 }
23193e513d1cd69 Mark Fasheh 2007-09-12 799 }
23193e513d1cd69 Mark Fasheh 2007-09-12 800
44acc46d182ff36 Ivan Pravdin 2025-07-07 801 if (le16_to_cpu(el->l_next_free_rec) == 0) {
44acc46d182ff36 Ivan Pravdin 2025-07-07 802 ret = ocfs2_error(inode->i_sb,
44acc46d182ff36 Ivan Pravdin 2025-07-07 803 "Inode %lu has empty extent list at depth %u\n",
44acc46d182ff36 Ivan Pravdin 2025-07-07 804 inode->i_ino,
44acc46d182ff36 Ivan Pravdin 2025-07-07 805 le16_to_cpu(el->l_tree_depth));
44acc46d182ff36 Ivan Pravdin 2025-07-07 806 goto out;
44acc46d182ff36 Ivan Pravdin 2025-07-07 807 }
44acc46d182ff36 Ivan Pravdin 2025-07-07 808
9b7895efac906d6 Mark Fasheh 2008-11-12 809 found = 0;
9b7895efac906d6 Mark Fasheh 2008-11-12 810 for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
9b7895efac906d6 Mark Fasheh 2008-11-12 811 rec = &el->l_recs[i];
9b7895efac906d6 Mark Fasheh 2008-11-12 812
9b7895efac906d6 Mark Fasheh 2008-11-12 813 if (le32_to_cpu(rec->e_cpos) <= major_hash) {
9b7895efac906d6 Mark Fasheh 2008-11-12 814 found = 1;
9b7895efac906d6 Mark Fasheh 2008-11-12 815 break;
9b7895efac906d6 Mark Fasheh 2008-11-12 816 }
9b7895efac906d6 Mark Fasheh 2008-11-12 817 }
9b7895efac906d6 Mark Fasheh 2008-11-12 818
9b7895efac906d6 Mark Fasheh 2008-11-12 819 if (!found) {
7ecef14ab1db961 Joe Perches 2015-09-04 820 ret = ocfs2_error(inode->i_sb,
7ecef14ab1db961 Joe Perches 2015-09-04 @821 "Inode %lu has bad extent record (%u, %u, 0) in btree\n",
7ecef14ab1db961 Joe Perches 2015-09-04 822 inode->i_ino,
82a88475c352f95 Shaurya Rane 2025-10-05 823 eb_bh ? (unsigned long long)eb_bh->b_blocknr : 0);
9b7895efac906d6 Mark Fasheh 2008-11-12 824 goto out;
9b7895efac906d6 Mark Fasheh 2008-11-12 825 }
9b7895efac906d6 Mark Fasheh 2008-11-12 826
9b7895efac906d6 Mark Fasheh 2008-11-12 827 if (ret_phys_blkno)
9b7895efac906d6 Mark Fasheh 2008-11-12 828 *ret_phys_blkno = le64_to_cpu(rec->e_blkno);
9b7895efac906d6 Mark Fasheh 2008-11-12 829 if (ret_cpos)
9b7895efac906d6 Mark Fasheh 2008-11-12 830 *ret_cpos = le32_to_cpu(rec->e_cpos);
9b7895efac906d6 Mark Fasheh 2008-11-12 831 if (ret_clen)
9b7895efac906d6 Mark Fasheh 2008-11-12 832 *ret_clen = le16_to_cpu(rec->e_leaf_clusters);
9b7895efac906d6 Mark Fasheh 2008-11-12 833
9b7895efac906d6 Mark Fasheh 2008-11-12 834 out:
9b7895efac906d6 Mark Fasheh 2008-11-12 835 brelse(eb_bh);
9b7895efac906d6 Mark Fasheh 2008-11-12 836 return ret;
9b7895efac906d6 Mark Fasheh 2008-11-12 837 }
38760e243249f03 Mark Fasheh 2007-09-11 838
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 3+ messages in thread