diff options
authorRich Felker <>2013-06-29 00:02:38 -0400
committerRich Felker <>2013-06-29 00:02:38 -0400
commit17aef0b41e3d7cb37c476cbe2df26fc444518a64 (patch)
parent062f40ef3e56021f4a9902095867e35cce6d99c4 (diff)
prevent shmget from allocating objects that overflow ptrdiff_t
rather than returning an error, we have to increase the size argument so high that the kernel will have no choice but to fail. this is because POSIX only permits the EINVAL error for size errors when a new shared memory segment would be created; if it already exists, the size argument must be ignored. unfortunately Linux is non-conforming in this regard, but I want to keep the code correct in userspace anyway so that if/when Linux is fixed, the behavior applications see will be conforming.
1 files changed, 2 insertions, 0 deletions
diff --git a/src/ipc/shmget.c b/src/ipc/shmget.c
index 61fb11d9..b44f9d68 100644
--- a/src/ipc/shmget.c
+++ b/src/ipc/shmget.c
@@ -1,9 +1,11 @@
#include <sys/shm.h>
+#include <stdint.h>
#include "syscall.h"
#include "ipc.h"
int shmget(key_t key, size_t size, int flag)
+ if (size > PTRDIFF_MAX) size = SIZE_MAX;
#ifdef SYS_shmget
return syscall(SYS_shmget, key, size, flag);