Reject size=0 before calling roundup_pow_of_two().
include/linux/log2.h documents roundup_pow_of_two() as:
- the result is undefined when n == 0
With CONFIG_UBSAN_SHIFT=y, a size=0 histogram trigger reports:
UBSAN: shift-out-of-bounds in include/linux/log2.h
shift exponent 64 is too large for 64-bit type 'long unsigned int'
Tested on x86_64 QEMU: size=0 is rejected without UBSAN warnings,
and the histogram modifier and parser tests pass.
Fixes: 7ef224d1d0e3 ("tracing: Add 'hist' event trigger command")
Cc: [email protected]
Signed-off-by: Jaewon Jung <[email protected]>
---
kernel/trace/trace_events_hist.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index f39fa8942673..3de794c7f5b2 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1430,6 +1430,11 @@ static int parse_map_size(char *str)
if (ret)
goto out;
+ if (!size) {
+ ret = -EINVAL;
+ goto out;
+ }
+
map_bits = ilog2(roundup_pow_of_two(size));
if (map_bits < TRACING_MAP_BITS_MIN ||
map_bits > TRACING_MAP_BITS_MAX)
--
2.43.0
