* [committed] Fix ubsan triggered in gdb-add-index.sh
@ 2021-03-15 10:55 Tom de Vries
0 siblings, 0 replies; only message in thread
From: Tom de Vries @ 2021-03-15 10:55 UTC (permalink / raw)
To: dwz, jakub, mark
Hi,
When compiling with CFLAGS="-O0 -ggdb3 -fsanitize=undefined"
LDFLAGS="-fsanitize=undefined' and running the testsuite, we run into:
...
dwz.c:573:64: runtime error: left shift of 144 by 24 places cannot be \
represented in type 'int'
FAIL: src/testsuite/dwz.tests/gdb-add-index.sh
...
The problem is here in buf_read_ule32:
...
static inline uint32_t
buf_read_ule32 (unsigned char *data)
{
return data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
...
The data[3] is an unsigned char, which is promoted to int when used as shift
operand, which causes the shift to be a signed one, which can result in
undefined behaviour when shifting into the sign bit.
Fix this by casting to unsigned int. Likewise in buf_read_ube32.
Committed to trunk.
Thanks,
- Tom
Fix ubsan triggered in gdb-add-index.sh
2021-03-15 Tom de Vries <tdevries@suse.de>
* dwz.c (buf_read_ule32, buf_read_ube32): Avoid undefined signed
left-shift behaviour.
---
dwz.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/dwz.c b/dwz.c
index d41e26e..54b4bda 100644
--- a/dwz.c
+++ b/dwz.c
@@ -570,13 +570,15 @@ buf_read_ube16 (unsigned char *data)
static inline uint32_t
buf_read_ule32 (unsigned char *data)
{
- return data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
+ return (data[0] | (data[1] << 8) | (data[2] << 16)
+ | ((unsigned int)data[3] << 24));
}
static inline uint32_t
buf_read_ube32 (unsigned char *data)
{
- return data[3] | (data[2] << 8) | (data[1] << 16) | (data[0] << 24);
+ return (data[3] | (data[2] << 8) | (data[1] << 16)
+ | ((unsigned int)data[0] << 24));
}
static inline uint64_t
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