diff options
| author | David Lee <david.lee@trailofbits.com> | 2026-07-08 10:17:09 +0000 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2026-07-09 15:35:53 +0200 |
| commit | cac0cb07f29ccfb373fd4a36c81e908ef3ce608c (patch) | |
| tree | 9b8c47050d282ef9dd31f76410fe858cd1feeffc | |
| parent | fb0601134c7e51728bd098abc6909315de1e5d86 (diff) | |
udf: reject VAT indexes equal to the entry count
UDF 1.50 virtual partition mapping uses the VAT as an array of physical
block mappings. s_num_entries stores the number of entries in that array,
not the highest valid index. The valid VAT indexes are therefore below
s_num_entries.
udf_get_pblock_virt15() currently rejects only indexes greater than
s_num_entries. A crafted image can request index s_num_entries, pass the
bounds check, and make the kernel read one entry past the allocated VAT table.
Change the check to reject block >= s_num_entries, so the count is handled as
an exclusive upper bound.
A crafted UDF image reproduced this on origin/master commit
0e35b9b6ec0ffcc5e23cbdec09f5c622ad532b53 with a KASAN slab-out-of-bounds
report in udf_get_pblock_virt15().
Trail of Bits has a reproducer that triggers kernel panic demonstrating the bug, and can share it if needed.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: David Lee <david.lee@trailofbits.com>
Assisted-by: Codex:gpt-5.5
Link: https://patch.msgid.link/20260708101712.1706564-1-david.lee@trailofbits.com
Signed-off-by: Jan Kara <jack@suse.cz>
| -rw-r--r-- | fs/udf/partition.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/udf/partition.c b/fs/udf/partition.c index 2b85c9501bed..ad8dcedca263 100644 --- a/fs/udf/partition.c +++ b/fs/udf/partition.c @@ -55,7 +55,7 @@ uint32_t udf_get_pblock_virt15(struct super_block *sb, uint32_t block, map = &sbi->s_partmaps[partition]; vdata = &map->s_type_specific.s_virtual; - if (block > vdata->s_num_entries) { + if (block >= vdata->s_num_entries) { udf_debug("Trying to access block beyond end of VAT (%u max %u)\n", block, vdata->s_num_entries); return 0xFFFFFFFF; |