From 296db618e9d1862aea788e90e751b4999db41a2a Mon Sep 17 00:00:00 2001 From: Even Rouault Date: Wed, 12 Jan 2022 23:43:03 +0100 Subject: [PATCH] json_escape_str(): avoid harmless unsigned integer overflow Current behaviour is perfectly valid, since wrap-over upon overflow is well defined behaviour for unsigned types, but it is nevertheless nice to be able to build with -fsanitize=undefined,unsigned-integer-overflow There is no significant effect on the generated assembly as can be seen on the diff of objdump -d output on a optimized build (the compiler just decided to switch the order of a comparison): @@ -135,8 +135,8 @@ 1d0: 0f 84 70 ff ff ff je 146 1d6: 4c 3b 24 24 cmp (%rsp),%r12 1da: 0f 85 2d ff ff ff jne 10d - 1e0: 49 39 f4 cmp %rsi,%r12 - 1e3: 0f 87 b7 00 00 00 ja 2a0 + 1e0: 4c 39 e6 cmp %r12,%rsi + 1e3: 0f 82 b7 00 00 00 jb 2a0 1e9: 48 8b 44 24 18 mov 0x18(%rsp),%rax 1ee: 64 48 33 04 25 28 00 xor %fs:0x28,%rax 1f5: 00 00 --- json_object.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/json_object.c b/json_object.c index d59a317..1e4f86d 100644 --- a/json_object.c +++ b/json_object.c @@ -180,8 +180,9 @@ static int json_escape_str(struct printbuf *pb, const char *str, size_t len, int { size_t pos = 0, start_offset = 0; unsigned char c; - while (len--) + while (len) { + --len; c = str[pos]; switch (c) { -- 2.49.0