diff options
| author | Chang S. Bae <chang.seok.bae@intel.com> | 2021-05-18 13:03:19 -0700 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-05-19 12:40:30 +0200 |
| commit | 2beb4a53fc3f1081cedc1c1a198c7f56cc4fc60c (patch) | |
| tree | 06304bf99dde06fa21c6631e428048a93783ef8d /include/linux/sched/signal.h | |
| parent | bdf6c8b84a4fa726c382ef6d3518f3ae123a7ebd (diff) | |
x86/signal: Detect and prevent an alternate signal stack overflow
The kernel pushes context on to the userspace stack to prepare for the
user's signal handler. When the user has supplied an alternate signal
stack, via sigaltstack(2), it is easy for the kernel to verify that the
stack size is sufficient for the current hardware context.
Check if writing the hardware context to the alternate stack will exceed
it's size. If yes, then instead of corrupting user-data and proceeding with
the original signal handler, an immediate SIGSEGV signal is delivered.
Refactor the stack pointer check code from on_sig_stack() and use the new
helper.
While the kernel allows new source code to discover and use a sufficient
alternate signal stack size, this check is still necessary to protect
binaries with insufficient alternate signal stack size from data
corruption.
Fixes: c2bc11f10a39 ("x86, AVX-512: Enable AVX-512 States Context Switch")
Reported-by: Florian Weimer <fweimer@redhat.com>
Suggested-by: Jann Horn <jannh@google.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Len Brown <len.brown@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20210518200320.17239-6-chang.seok.bae@intel.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=153531
Diffstat (limited to 'include/linux/sched/signal.h')
| -rw-r--r-- | include/linux/sched/signal.h | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 3f6a0fcaa10c..ae60f838ebb9 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -537,6 +537,17 @@ static inline int kill_cad_pid(int sig, int priv) #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0) #define SEND_SIG_PRIV ((struct kernel_siginfo *) 1) +static inline int __on_sig_stack(unsigned long sp) +{ +#ifdef CONFIG_STACK_GROWSUP + return sp >= current->sas_ss_sp && + sp - current->sas_ss_sp < current->sas_ss_size; +#else + return sp > current->sas_ss_sp && + sp - current->sas_ss_sp <= current->sas_ss_size; +#endif +} + /* * True if we are on the alternate signal stack. */ @@ -554,13 +565,7 @@ static inline int on_sig_stack(unsigned long sp) if (current->sas_ss_flags & SS_AUTODISARM) return 0; -#ifdef CONFIG_STACK_GROWSUP - return sp >= current->sas_ss_sp && - sp - current->sas_ss_sp < current->sas_ss_size; -#else - return sp > current->sas_ss_sp && - sp - current->sas_ss_sp <= current->sas_ss_size; -#endif + return __on_sig_stack(sp); } static inline int sas_ss_flags(unsigned long sp) |