From: Eric Biggers <ebiggers3@...>

commit f97238373b8662a6d580e204df2e7bcbfa43e27a upstream.

Accessing more than one byte from a symbol declared simply 'char' is undefined
behavior, as reported by UBSAN:

UBSAN: Undefined behaviour in drivers/base/power/trace.c:178:18
load of address ffffffff8203fc78 with insufficient space
for an object of type 'char'

Avoid this by declaring the symbols as arrays.

Signed-off-by: Eric Biggers <ebiggers3@...>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...>
Signed-off-by: Ben Hutchings <ben.hutchings@...>
---
drivers/base/power/trace.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index a311cfa4c5bd..a6975795e7f3 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -166,14 +166,14 @@ void generate_pm_trace(const void *tracedata, unsigned int user)
}
EXPORT_SYMBOL(generate_pm_trace);

-extern char __tracedata_start, __tracedata_end;
+extern char __tracedata_start[], __tracedata_end[];
static int show_file_hash(unsigned int value)
{
int match;
char *tracedata;

match = 0;
- for (tracedata = &__tracedata_start ; tracedata < &__tracedata_end ;
+ for (tracedata = __tracedata_start ; tracedata < __tracedata_end ;
tracedata += 2 + sizeof(unsigned long)) {
unsigned short lineno = *(unsigned short *)tracedata;
const char *file = *(const char **)(tracedata + 2);
--
2.10.2



--
Ben Hutchings
Software Developer, Codethink Ltd.