Eric Lee / linux-smarc-t335x-v3.2

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Commit 6c826818ff55eae7702b778b5f8bdf765af3b2af

Authored by Paul Menage
Committed by Linus Torvalds
1 parent bcf8039ed4
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

/proc/sysvipc/shm: fix 32-bit truncation of segment sizes 

sysvipc_shm_proc_show() picks between format strings (based on the
expected maximum length of a SHM segment) in a way that prevents gcc from
performing format checks on the seq_printf() parameters.  This hid two
format errors - shp->shm_segsz and shp->shm_nattach are both unsigned
long, but were being printed as unsigned int and signed int respectively.
This leads to 32-bit truncation of SHM segment sizes reported in
/proc/sysvipc/shm.  (And for nattach, but that's less of a problem for
most users).

This patch makes the format string directly visible to gcc's format
specifier checker, and fixes the two broken format specifiers.

Signed-off-by: Paul Menage <menage@google.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 8 additions and 8 deletions Side-by-side Diff

... ... @@ -1058,16 +1058,16 @@
1058 1058 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1059 1059 {
1060 1060 struct shmid_kernel *shp = it;
1061   - char *format;
1062 1061  
1063   -#define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
1064   -#define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
  1062 +#if BITS_PER_LONG <= 32
  1063 +#define SIZE_SPEC "%10lu"
  1064 +#else
  1065 +#define SIZE_SPEC "%21lu"
  1066 +#endif
1065 1067  
1066   - if (sizeof(size_t) <= sizeof(int))
1067   - format = SMALL_STRING;
1068   - else
1069   - format = BIG_STRING;
1070   - return seq_printf(s, format,
  1068 + return seq_printf(s,
  1069 + "%10d %10d %4o " SIZE_SPEC " %5u %5u "
  1070 + "%5lu %5u %5u %5u %5u %10lu %10lu %10lu\n",
1071 1071 shp->shm_perm.key,
1072 1072 shp->shm_perm.id,
1073 1073 shp->shm_perm.mode,