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lib: add stream_rewind_getp()

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stream_forward_getp() cannot be used with negative numbers due to the
size_t argument, we'll end up doing overflow arithmetic.

Signed-off-by: Quentin Young <qlyoung@nvidia.com>
This commit is contained in:
Quentin Young 2020-09-02 16:43:29 -04:00
parent e6464fdc18
commit 06cf2c0c36
2 changed files with 32 additions and 0 deletions
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24
lib/stream.c
View file

@ -268,6 +268,30 @@ bool stream_forward_getp2(struct stream *s, size_t size)
return true; return true;
} }
void stream_rewind_getp(struct stream *s, size_t size)
{
STREAM_VERIFY_SANE(s);
if (size > s->getp || !GETP_VALID(s, s->getp - size)) {
STREAM_BOUND_WARN(s, "rewind getp");
return;
}
s->getp -= size;
}
bool stream_rewind_getp2(struct stream *s, size_t size)
{
STREAM_VERIFY_SANE(s);
if (size > s->getp || !GETP_VALID(s, s->getp - size))
return false;
s->getp -= size;
return true;
}
void stream_forward_endp(struct stream *s, size_t size) void stream_forward_endp(struct stream *s, size_t size)
{ {
STREAM_VERIFY_SANE(s); STREAM_VERIFY_SANE(s);

8
lib/stream.h
View file

@ -174,6 +174,8 @@ extern void stream_set_getp(struct stream *, size_t);
extern void stream_set_endp(struct stream *, size_t); extern void stream_set_endp(struct stream *, size_t);
extern void stream_forward_getp(struct stream *, size_t); extern void stream_forward_getp(struct stream *, size_t);
extern bool stream_forward_getp2(struct stream *, size_t); extern bool stream_forward_getp2(struct stream *, size_t);
extern void stream_rewind_getp(struct stream *s, size_t size);
extern bool stream_rewind_getp2(struct stream *s, size_t size);
extern void stream_forward_endp(struct stream *, size_t); extern void stream_forward_endp(struct stream *, size_t);
extern bool stream_forward_endp2(struct stream *, size_t); extern bool stream_forward_endp2(struct stream *, size_t);
@ -461,6 +463,12 @@ static inline const uint8_t *ptr_get_be32(const uint8_t *ptr, uint32_t *out)
goto stream_failure; \ goto stream_failure; \
} while (0) } while (0)
#define STREAM_REWIND_GETP(STR, SIZE) \
do { \
if (!stream_rewind_getp2((STR), (SIZE))) \
goto stream_failure; \
} while (0)
#define STREAM_FORWARD_ENDP(STR, SIZE) \ #define STREAM_FORWARD_ENDP(STR, SIZE) \
do { \ do { \
if (!stream_forward_endp2((STR), (SIZE))) \ if (!stream_forward_endp2((STR), (SIZE))) \