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authorHeiko Carstens <hca@linux.ibm.com>2024-04-29 15:28:46 +0300
committerAlexander Gordeev <agordeev@linux.ibm.com>2024-05-14 14:37:06 +0300
commitcd58109283944ea8bdcd0a8211a86cbd2450716a (patch)
tree3efcc9cea02174f0a29c7e2a2bb26e58771b67e5
parent87eceb17a987802aeee718be4decd19b56fc8e33 (diff)
downloadlinux-cd58109283944ea8bdcd0a8211a86cbd2450716a.tar.xz
s390/stacktrace: Improve detection of invalid instruction pointers
Add basic checks to identify invalid instruction pointers when walking stack frames: Instruction pointers must - have even addresses - be larger than mmap_min_addr - lower than the asce_limit of the process Alternatively it would also be possible to walk page tables similar to fast GUP and verify that the mapping of the corresponding page is executable, however that seems to be overkill. Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support") Reviewed-by: Jens Remus <jremus@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
-rw-r--r--arch/s390/kernel/stacktrace.c26
1 files changed, 22 insertions, 4 deletions
diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index 1c9e3b7739a2..b4485b0c7f06 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -77,6 +77,21 @@ static inline bool store_ip(stack_trace_consume_fn consume_entry, void *cookie,
return consume_entry(cookie, ip);
}
+static inline bool ip_invalid(unsigned long ip)
+{
+ /*
+ * Perform some basic checks if an instruction address taken
+ * from unreliable source is invalid.
+ */
+ if (ip & 1)
+ return true;
+ if (ip < mmap_min_addr)
+ return true;
+ if (ip >= current->mm->context.asce_limit)
+ return true;
+ return false;
+}
+
void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie,
struct perf_callchain_entry_ctx *entry,
const struct pt_regs *regs, bool perf)
@@ -87,6 +102,8 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
if (is_compat_task())
return;
+ if (!current->mm)
+ return;
ip = instruction_pointer(regs);
if (!store_ip(consume_entry, cookie, entry, perf, ip))
return;
@@ -101,15 +118,16 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
sf = (void __user *)sp;
if (__get_user(ip, &sf->gprs[8]))
break;
- if (ip & 0x1) {
+ if (ip_invalid(ip)) {
/*
* If the instruction address is invalid, and this
* is the first stack frame, assume r14 has not
* been written to the stack yet. Otherwise exit.
*/
- if (first && !(regs->gprs[14] & 0x1))
- ip = regs->gprs[14];
- else
+ if (!first)
+ break;
+ ip = regs->gprs[14];
+ if (ip_invalid(ip))
break;
}
if (!store_ip(consume_entry, cookie, entry, perf, ip))