From: Paul Menage Date: Thu, 12 Jun 2008 22:21:49 +0000 (-0700) Subject: /proc/sysvipc/shm: fix 32-bit truncation of segment sizes X-Git-Tag: v2.6.26-rc7~48 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6c826818ff55eae7702b778b5f8bdf765af3b2af;p=linux-2.6 /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 Cc: Nadia Derbey Cc: Manfred Spraul Cc: Pierre Peiffer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/ipc/shm.c b/ipc/shm.c index d05f6b5649..790240cd06 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -1058,16 +1058,16 @@ asmlinkage long sys_shmdt(char __user *shmaddr) 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,