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authorPeter Collingbourne <pcc@google.com>2020-11-20 12:33:45 -0800
committerEric W. Biederman <ebiederm@xmission.com>2020-11-23 10:31:06 -0600
commit6ac05e832a9e96f9b1c42a8917cdd317d7b6c8fa (patch)
tree72e13727569f07efa33909831e2de1e7e9743bef /kernel/signal.c
parenta54f0dfda754c5cecc89a14dab68a3edc1e497b5 (diff)
signal: define the SA_EXPOSE_TAGBITS bit in sa_flags
Architectures that support address tagging, such as arm64, may want to expose fault address tag bits to the signal handler to help diagnose memory errors. However, these bits have not been previously set, and their presence may confuse unaware user applications. Therefore, introduce a SA_EXPOSE_TAGBITS flag bit in sa_flags that a signal handler may use to explicitly request that the bits are set. The generic signal handler APIs expect to receive tagged addresses. Architectures may specify how to untag addresses in the case where SA_EXPOSE_TAGBITS is clear by defining the arch_untagged_si_addr function. Signed-off-by: Peter Collingbourne <pcc@google.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Link: https://linux-review.googlesource.com/id/I16dd0ed2081f091fce97be0190cb8caa874c26cb Link: https://lkml.kernel.org/r/13cf24d00ebdd8e1f55caf1821c7c29d54100191.1605904350.git.pcc@google.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 8f34819e80de..26018c59821d 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2524,6 +2524,26 @@ static int ptrace_signal(int signr, kernel_siginfo_t *info)
return signr;
}
+static void hide_si_addr_tag_bits(struct ksignal *ksig)
+{
+ switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
+ case SIL_FAULT:
+ case SIL_FAULT_MCEERR:
+ case SIL_FAULT_BNDERR:
+ case SIL_FAULT_PKUERR:
+ ksig->info.si_addr = arch_untagged_si_addr(
+ ksig->info.si_addr, ksig->sig, ksig->info.si_code);
+ break;
+ case SIL_KILL:
+ case SIL_TIMER:
+ case SIL_POLL:
+ case SIL_CHLD:
+ case SIL_RT:
+ case SIL_SYS:
+ break;
+ }
+}
+
bool get_signal(struct ksignal *ksig)
{
struct sighand_struct *sighand = current->sighand;
@@ -2761,6 +2781,10 @@ relock:
spin_unlock_irq(&sighand->siglock);
ksig->sig = signr;
+
+ if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
+ hide_si_addr_tag_bits(ksig);
+
return ksig->sig > 0;
}

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