From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 References: <20180627012421.80B8F24E094@nmr-admin> In-Reply-To: <20180627012421.80B8F24E094@nmr-admin> From: Geert Uytterhoeven Date: Wed, 27 Jun 2018 15:30:59 +0200 Message-ID: Subject: Re: Subject: [PATCH RFC] block: fix Amiga RDB partition support for disks >= 2 TB To: Michael Schmitz Cc: Jens Axboe , geert@linux-m68k.org-r, jdow , Martin Steigerwald , linux-m68k , linux-block@vger.kernel.org Content-Type: text/plain; charset="UTF-8" List-ID: Hi Michael, Thanks for your patch! On Wed, Jun 27, 2018 at 4:47 AM 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 > , and the fix was created by the RDB author, > Joanne Dow . 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 > Message-ID: <201206192146.09327.Martin@lichtvoll.de> > Signed-off-by: Michael Schmitz > Tested-by: Martin Steigerwald > Tested-by: Michael Schmitz > --- > 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 -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org 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