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>
---
ipc/shm.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
Index: shm-2.6.26-rc5-mm2/ipc/shm.c
===================================================================
--- shm-2.6.26-rc5-mm2.orig/ipc/shm.c
+++ shm-2.6.26-rc5-mm2/ipc/shm.c
@@ -1062,16 +1062,16 @@ asmlinkage long sys_shmdt(char __user *s
static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
{
struct shmid_kernel *shp = it;
- char *format;
-#define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
-#define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
+#if BITS_PER_LONG <= 32
+#define SIZE_SPEC "%10lu"
+#else
+#define SIZE_SPEC "%21lu"
+#endif
- if (sizeof(size_t) <= sizeof(int))
- format = SMALL_STRING;
- else
- format = BIG_STRING;
- return seq_printf(s, format,
+ return seq_printf(s,
+ "%10d %10d %4o " SIZE_SPEC " %5u %5u "
+ "%5lu %5u %5u %5u %5u %10lu %10lu %10lu\n",
shp->shm_perm.key,
shp->shm_perm.id,
shp->shm_perm.mode,
--
