musl - musl - an implementation of the standard library for Linux-based systems

musl - an implementation of the standard library for Linux-based systems

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author	rofl0r <retnyg@gmx.net>	2014年03月13日 20:27:55 +0100
committer	rofl0r <retnyg@gmx.net>	2014年03月13日 20:52:34 +0100
commit	2b47a7aff24bbfbe7ba89fc6d542acc9f5493ae2 (patch)
tree	107f246032a3be3154cacbece31002dbaf947ea9 /src/ipc/semctl.c
parent	7673acd31503016f2af93e187aac98da07af42b4 (diff)
download	musl-2b47a7aff24bbfbe7ba89fc6d542acc9f5493ae2.tar.gz

semctl: fix UB causing crashes on powerpc

it's UB to fetch variadic args when none are passed, and this caused real crashes on ppc due to its calling convention, which defines that for variadic functions aggregate types be passed as pointers. the assignment caused that pointer to get dereferenced, resulting in a crash.

Diffstat (limited to 'src/ipc/semctl.c')

-rw-r--r--

src/ipc/semctl.c

1 files changed, 8 insertions, 4 deletions

diff --git a/src/ipc/semctl.c b/src/ipc/semctl.c
index 3d79f503..673a9a8c 100644
--- a/src/ipc/semctl.c
+++ b/src/ipc/semctl.c

@@ -11,11 +11,15 @@ union semun {

int semctl(int id, int num, int cmd, ...)

{

- union semun arg;

+ union semun arg = {0};

va_list ap;

- va_start(ap, cmd);

- arg = va_arg(ap, union semun);

- va_end(ap);

+ switch (cmd) {

+ case SETVAL: case GETALL: case SETALL: case IPC_STAT: case IPC_SET:

+ case IPC_INFO: case SEM_INFO: case SEM_STAT:

+ va_start(ap, cmd);

+ arg = va_arg(ap, union semun);

+ va_end(ap);

+ }

#ifdef SYS_semctl

return syscall(SYS_semctl, id, num, cmd | IPC_64, arg.buf);

#else

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