From 41b27154874b3a40d6673052d08c8e9fd0c6404f Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Tue, 22 Mar 2016 14:27:54 -0700 Subject: kernel/signal.c: add compile-time check for __ARCH_SI_PREAMBLE_SIZE The value of __ARCH_SI_PREAMBLE_SIZE defines the size (including padding) of the part of the struct siginfo that is before the union, and it is then used to calculate the needed padding (SI_PAD_SIZE) to make the size of struct siginfo equal to 128 (SI_MAX_SIZE) bytes. Depending on the target architecture and word width it equals to either 3 or 4 times sizeof int. Since the very beginning we had __ARCH_SI_PREAMBLE_SIZE wrong on the parisc architecture for the 64bit kernel build. It's even more frustrating, because it can easily be checked at compile time if the value was defined correctly. This patch adds such a check for the correctness of __ARCH_SI_PREAMBLE_SIZE in the hope that it will prevent existing and future architectures from running into the same problem. I refrained from replacing __ARCH_SI_PREAMBLE_SIZE by offsetof() in copy_siginfo() in include/asm-generic/siginfo.h, because a) it doesn't make any difference and b) it's used in the Documentation/kmemcheck.txt example. I ran this patch through the 0-DAY kernel test infrastructure and only the parisc architecture triggered as expected. That means that this patch should be OK for all major architectures. Signed-off-by: Helge Deller Cc: Stephen Rothwell Cc: Michael Ellerman Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/signal.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/signal.c') diff --git a/kernel/signal.c b/kernel/signal.c index fe8ed298373c..aa9bf00749c1 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3585,6 +3585,10 @@ __weak const char *arch_vma_name(struct vm_area_struct *vma) void __init signals_init(void) { + /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */ + BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE + != offsetof(struct siginfo, _sifields._pad)); + sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); } -- cgit v1.2.3