signal(x86-64): alternative signal stack wraparound occurs

PATCH In review Shi Weihua 1 participant 1 message Oct 3, 2007

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Shi Weihua

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2007-10-03 08:07 UTC #0 lore raw

PATCH 3/3 signal(x86-64): alternative signal stack wraparound occurs

Fixing alternative signal stack wraparound.

If a process uses alternative signal stack by using sigaltstack()
and that stack overflow, stack wraparound occurs.
This patch checks whether the signal frame is on the alternative stack. If the frame is not on there, kill a signal SIGSEGV to the process forcedly then the process will be terminated.

This patch is for x86-64,version is 2.6.23-rc8.

Signed-off-by Shi Weihua <[email protected]>

arch/x86_64/ia32/ia32_signal.c +8 -0

diff -pur linux-2.6.23-rc8.orig/arch/x86_64/ia32/ia32_signal.c linux-2.6.23-rc8/arch/x86_64/ia32/ia32_signal.c
@@ -428,6 +428,10 @@ int ia32_setup_frame(int sig, struct k_s
 
 	frame = get_sigframe(ka, regs, sizeof(*frame));
 
+	if ((ka->sa.sa_flags & SA_ONSTACK)
+		&& (sas_ss_flags((unsigned long) frame) == 0))
+		goto give_sigsegv;
+
 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		goto give_sigsegv;

@@ -518,6 +522,10 @@ int ia32_setup_rt_frame(int sig, struct
 
 	frame = get_sigframe(ka, regs, sizeof(*frame));
 
+	if ((ka->sa.sa_flags & SA_ONSTACK)
+		&& (sas_ss_flags((unsigned long) frame) == 0))
+		goto give_sigsegv;
+
 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		goto give_sigsegv;

arch/x86_64/kernel/signal.c +4 -0

diff -pur linux-2.6.23-rc8.orig/arch/x86_64/kernel/signal.c linux-2.6.23-rc8/arch/x86_64/kernel/signal.c
@@ -235,6 +235,10 @@ static int setup_rt_frame(int sig, struc
 	} else
 		frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
 
+	if ((ka->sa.sa_flags & SA_ONSTACK)
+		&& (sas_ss_flags((unsigned long) frame) == 0))
+		goto give_sigsegv;
+
 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		goto give_sigsegv;