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signal: Properly deliver SIGSEGV from x86 uprobes

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[ Upstream commit 4a63c1ffd3 ]

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: 791eca1010 ("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>
This commit is contained in:
Eric W. Biederman
2018-07-19 20:48:30 -05:00
committed by Greg Kroah-Hartman
parent dbe380adfc
commit 75c36953ad
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/uprobes.c
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@@ -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;