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Subject[PATCH AUTOSEL 4.9 39/64] signal: Properly deliver SIGSEGV from x86 uprobes
From: "Eric W. Biederman" <>

[ Upstream commit 4a63c1ffd384ebdce40aac9c997dab68379137be ]

For userspace to tell the difference between an random signal
and an exception, the exception must include siginfo information.

Using SEND_SIG_FORCED for SIGSEGV is thus wrong, and it will result in
userspace seeing si_code == SI_USER (like a random signal) instead of
si_code == SI_KERNEL or a more specific si_code as all exceptions

Therefore replace force_sig_info(SIGSEGV, SEND_SIG_FORCE, current)
with force_sig(SIG_SEGV, current) which gets this right and is shorter
and easier to type.

Fixes: 791eca10107f ("uretprobes/x86: Hijack return address")
Reviewed-by: Thomas Gleixner <>
Signed-off-by: "Eric W. Biederman" <>
Signed-off-by: Sasha Levin <>
arch/x86/kernel/uprobes.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index e35466afe989d..eac679ab543f6 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -983,7 +983,7 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs
pr_err("uprobe: return address clobbered: pid=%d, %%sp=%#lx, "
"%%ip=%#lx\n", current->pid, regs->sp, regs->ip);

- force_sig_info(SIGSEGV, SEND_SIG_FORCED, current);
+ force_sig(SIGSEGV, current);

return -1;
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