Hi Michael,
Thanks for your patch!
On Wed, Jun 27, 2018 at 4:47 AM <schmitzmic@xxxxxxxxx> wrote:
From 5299e0e64dfb33ac3a1f3137b42178734ce20087 Mon Sep 17 00:00:00 2001
??
The Amiga RDB partition parser module uses int for partition sector
address and count, which will overflow for disks 2 TB and larger.
Use sector_t as type for sector address and size (as expected by
put_partition) to allow using such disks without danger of data
corruption.
Note that sector_t is not guaranteed to be 64-bit:
#ifdef CONFIG_LBDAF
typedef u64 sector_t;
typedef u64 blkcnt_t;
#else
typedef unsigned long sector_t;
typedef unsigned long blkcnt_t;
#endif
And it seems CONFIG_LBDAF can still be disabled on 32-bit...
This bug was reported originally in 2012 by Martin Steigerwald
<Martin@xxxxxxxxxxxx>, and the fix was created by the RDB author,
Joanne Dow <jdow@xxxxxxxxxxxxx>. The patch had been discussed and
reviewed on linux-m68k at that time but never officially submitted.
Following a stern warning by Joanne, a warning is printed if any
partition is found to overflow the old 32 bit calculations, on the
grounds that such a partition would be misparses on legacy 32 bit
systems (other than Linux).
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>
Tested-by: Martin Steigerwald <Martin@xxxxxxxxxxxx>
Tested-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
---
block/partitions/amiga.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
index 5609366..42c3f38 100644
--- a/block/partitions/amiga.c
+++ b/block/partitions/amiga.c
@@ -32,7 +32,8 @@ int amiga_partition(struct parsed_partitions *state)
unsigned char *data;
struct RigidDiskBlock *rdb;
struct PartitionBlock *pb;
- int start_sect, nr_sects, blk, part, res = 0;
+ sector_t start_sect, nr_sects;
As sector_t can still be 32-bit, I think you should use an explicit u64 here.
+ int blk, part, res = 0;
int blksize = 1; /* Multiplier for disk block size */
int slot = 1;
char b[BDEVNAME_SIZE];
@@ -111,6 +112,16 @@ int amiga_partition(struct parsed_partitions *state)
be32_to_cpu(pb->pb_Environment[3]) *
be32_to_cpu(pb->pb_Environment[5]) *
blksize;
Without adding any unsigned long long or ULL stuff to the calculations
for start_sect and nr_sects above, the math will still be done using 32-bit
arithmetic. Or am I missing something?
+ if (start_sect > INT_MAX || nr_sects > INT_MAX
+ || (start_sect + nr_sects) > INT_MAX) {
+ pr_err("%s: Warning: RDB partition overflow!\n",
+ bdevname(state->bdev, b));
+ pr_err("%s: start 0x%llX size 0x%llX\n",
+ bdevname(state->bdev, b), start_sect,
+ nr_sects);
+ pr_err("%s: partition incompatible with 32 bit OS\n",
+ bdevname(state->bdev, b));
+ }
I don't know if the check above is really needed here.
There's also int vs. unsigned int. But see below.
put_partition(state,slot++,start_sect,nr_sects);
Given sector_t may be 32-bit, values may be truncated when calling
put_partition(), so you need to check for that.
Interestingly, even partition parsers that do use u64 (efi, ldm) or loff_t
(ibm) do not have such checks.
Perhaps put_partition() should take u64, and print a warning and ignore the
partition if conversion to sector_t involves truncation?
{
/* Be even more informative to aid mounting */
Gr{oetje,eeting}s,
Geert
