From: Denis Rastyogin <ger...@altlinux.org>
This error was discovered by fuzzing qemu-img.
When ph.ext_off has a sufficiently large value, the operation
le64_to_cpu(ph.ext_off) << BDRV_SECTOR_BITS in
parallels_read_format_extension() can cause an overflow in int64_t.
This overflow triggers the assert(ext_off > 0)
check in block/parallels-ext.c: parallels_read_format_extension(),
leading to a crash.
This commit adds a check to prevent overflow when shifting ph.ext_off
by BDRV_SECTOR_BITS, ensuring that the value remains within a valid range.
Reported-by: Leonid Reviakin <l.revia...@fobos-nt.ru>
Signed-off-by: Denis Rastyogin <ger...@altlinux.org>
---
block/parallels.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/block/parallels.c b/block/parallels.c
index 9205a0864f..8f2b58e1c9 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -1298,6 +1298,10 @@ static int parallels_open(BlockDriverState *bs, QDict
*options, int flags,
error_setg(errp, "Catalog too large");
return -EFBIG;
}
+ if (le64_to_cpu(ph.ext_off) >= (INT64_MAX >> BDRV_SECTOR_BITS)) {
+ error_setg(errp, "Invalid image: Too big offset");
+ return -EFBIG;
+ }
size = bat_entry_off(s->bat_size);
s->header_size = ROUND_UP(size, bdrv_opt_mem_align(bs->file->bs));
--
2.42.2
