signal: Properly deliver SIGSEGV from x86 uprobes

BugLink: https://bugs.launchpad.net/bugs/1853915
[ 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
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index a1e56ab3d805224809d08c4e90a4789092cad23e..e7b762d635b5e07faebf0a0a0f8f3890aff3da7a 100644 (file)
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -990,7 +990,7 @@ 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;