signal: Properly deliver SIGSEGV from x86 uprobes

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
deliver.

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 <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index deb576b23b7cf49817533d00555d0dc976c42486..843feb94a950168c60319e127f4df4568e1beb3c 100644 (file)
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -1086,7 +1086,7 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs
                pr_err("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;