Hi Michael,
On Sun, Oct 14, 2018 at 6:48 AM Michael Schmitz <schmitzmic@xxxxxxxxx> wrote:
The Amiga partition parser module uses signed int for partition sector
address and count, which will overflow for disks larger than 1 TB.
Use u64 as type for sector address and size to allow using disks up to
2 TB without LBD support, and disks larger than 2 TB with LBD. The RBD
format allows to specify disk sizes up to 2^128 bytes (though native
OS limitations reduce this somewhat, to max 2^68 bytes), so check for
u64 overflow carefully to protect against overflowing sector_t.
Bail out if sector addresses overflow 32 bits on kernels without LBD
support.
This bug was reported originally in 2012, and the fix was created by
the RDB author, Joanne Dow <jdow@xxxxxxxxxxxxx>. A patch had been
discussed and reviewed on linux-m68k at that time but never officially
submitted (now resubmitted as separate patch).
This patch adds additional error checking and warning messages.
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=43511
Reported-by: Martin Steigerwald <Martin@xxxxxxxxxxxx>
Message-ID: <201206192146.09327.Martin@xxxxxxxxxxxx>
Signed-off-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
---
Changes from RFC:
- use u64 instead of sector_t, since that may be u32 without LBD support
- check multiplication overflows each step - 3 u32 values may exceed u64!
- warn against use on AmigaDOS if partition data overflow u32 sector count.
- warn if partition CylBlocks larger than what's stored in the RDSK header.
- bail out if we were to overflow sector_t (32 or 64 bit).
Changes from v1:
Kars de Jong:
- use defines for magic offsets in DosEnvec struct
Geert Uytterhoeven:
- use u64 cast for multiplications of u32 numbers
- use array3_size for overflow checks
- change pr_err to pr_warn
- discontinue use of pr_cont
- reword log messages
- drop redundant nr_sects overflow test
- warn against 32 bit overflow for each affected partition
- skip partitions that overflow sector_t size instead of aborting scan
Changes from v2:
- further trim 32 bit overflow test
- correct duplicate types.h inclusion introduced in v2
Changes from v3:
- split off sector address type fix for independent review
- change blksize to unsigned
- use check_mul_overflow() instead of array3_size()
- rewrite checks to avoid 64 bit divisions in check_mul_overflow()
Changes from v5:
Geert Uytterhoeven:
- correct ineffective u64 cast to avoid 32 bit mult. overflow
- fix mult. overflow in partition block address calculation
Thanks for the updates!
Reviewed-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
with one suggestion for improvement below.
--- a/block/partitions/amiga.c
+++ b/block/partitions/amiga.c
@@ -83,12 +94,18 @@ int amiga_partition(struct parsed_partitions *state)
blk = be32_to_cpu(rdb->rdb_PartitionList);
put_dev_sector(sect);
for (part = 1; blk>0 && part<=16; part++, put_dev_sector(sect)) {
- blk *= blksize; /* Read in terms partition table understands */
+ /* Read in terms partition table understands */
+ if (check_mul_overflow(blk, (sector_t) blksize, &blk)) {
+ pr_err("Dev %s: overflow calculating partition block %llu!\n",
+ bdevname(state->bdev, b), (u64) blk);
+ res = -1;
+ goto rdb_done;
I would not fail hard, but try to use the first few partitions that lie
within sector_t size range.
i.e.
pr_err("Dev %s: overflow calculating partition
block %llu, skipping partitions %u and later\n",
bdevname(state->bdev, b), (u64) blk, part);
break;
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
