[PATCH 4.4-cip 14/23] signal: move the "sig < SIGRTMIN" check into siginmask(sig)


Ben Hutchings <ben.hutchings@...>
 

From: Oleg Nesterov <oleg@...>

commit 5c8ccefdf46c5f87d87b694c7fbc04941c2c99a5 upstream.

All the users of siginmask() must ensure that sig < SIGRTMIN. sig_fatal()
doesn't and this is wrong:

UBSAN: Undefined behaviour in kernel/signal.c:911:6
shift exponent 32 is too large for 32-bit type 'long unsigned int'

the patch doesn't add the neccesary check to sig_fatal(), it moves the
check into siginmask() and updates other callers.

Link: http://lkml.kernel.org/r/20160517195052.GA15187@redhat.com
Reported-by: Meelis Roos <mroos@...>
Signed-off-by: Oleg Nesterov <oleg@...>
Signed-off-by: Andrew Morton <akpm@...>
Signed-off-by: Linus Torvalds <torvalds@...>
Signed-off-by: Ben Hutchings <ben.hutchings@...>
---
include/linux/signal.h | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/include/linux/signal.h b/include/linux/signal.h
index d80259afb9e5..d822bd15dddc 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -400,7 +400,9 @@ int unhandled_signal(struct task_struct *tsk, int sig);
#else
#define rt_sigmask(sig) sigmask(sig)
#endif
-#define siginmask(sig, mask) (rt_sigmask(sig) & (mask))
+
+#define siginmask(sig, mask) \
+ ((sig) < SIGRTMIN && (rt_sigmask(sig) & (mask)))

#define SIG_KERNEL_ONLY_MASK (\
rt_sigmask(SIGKILL) | rt_sigmask(SIGSTOP))
@@ -421,14 +423,10 @@ int unhandled_signal(struct task_struct *tsk, int sig);
rt_sigmask(SIGCONT) | rt_sigmask(SIGCHLD) | \
rt_sigmask(SIGWINCH) | rt_sigmask(SIGURG) )

-#define sig_kernel_only(sig) \
- (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_ONLY_MASK))
-#define sig_kernel_coredump(sig) \
- (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_COREDUMP_MASK))
-#define sig_kernel_ignore(sig) \
- (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_IGNORE_MASK))
-#define sig_kernel_stop(sig) \
- (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_STOP_MASK))
+#define sig_kernel_only(sig) siginmask(sig, SIG_KERNEL_ONLY_MASK)
+#define sig_kernel_coredump(sig) siginmask(sig, SIG_KERNEL_COREDUMP_MASK)
+#define sig_kernel_ignore(sig) siginmask(sig, SIG_KERNEL_IGNORE_MASK)
+#define sig_kernel_stop(sig) siginmask(sig, SIG_KERNEL_STOP_MASK)

#define sig_user_defined(t, signr) \
(((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
--
2.10.2



--
Ben Hutchings
Software Developer, Codethink Ltd.

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