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Small fixes #91

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7a7a1aa
Fix dereferencing null pointer in oggpack_writeinit
bibendovsky May 4, 2023
e3075c3
Fix type cast in ogg_page_serialno and ogg_page_pageno
bibendovsky May 4, 2023
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2 changes: 1 addition & 1 deletion src/bitwise.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@ static const unsigned int mask8B[]=
void oggpack_writeinit(oggpack_buffer *b){
memset(b,0,sizeof(*b));
b->ptr=b->buffer=_ogg_malloc(BUFFER_INCREMENT);
b->buffer[0]='\0';
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This do not look correct. If malloc() fail, I doubt b->storage should get a non-zero value as the there is no storage available.

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This do not look correct. If malloc() fail, I doubt b->storage should get a non-zero value as the there is no storage available.

The fix do the check for a null. You can see this under the review conversation.

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I do not understand your comment. I see the addition of if(b->buffer) in your patch, but fail to see how this properly handle the case where malloc() return NULL, as it seem incomplete and returning a misleading state from the oggpack_writeinit() method. Why is your edition still modifying b->storage if there is no memory area pointed to by b->buffer?

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I created https://gitlab.xiph.org/xiph/ogg/-/merge_requests/26 with my proposed fix for the same issue, including updating the documentation to mention that the method can fail.

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I do not understand your comment. I see the addition of if(b->buffer) in your patch, but fail to see how this properly handle the case where malloc() return NULL

Conditional operator if (b->buffer) prevents from writing '\0' into b->buffer when it is null.

but fail to see how this properly handle the case where malloc() return NULL, as it seem incomplete and returning a misleading state from the oggpack_writeinit() method.

The commit do exactly what it says - nothing more, nothing less.
I could add another commit to address this exact issue (the incomplete state).

Why is your edition still modifying b->storage if there is no memory area pointed to by b->buffer?

That was in original code.

if(b->buffer) b->buffer[0]='\0';
b->storage=BUFFER_INCREMENT;
}

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8 changes: 4 additions & 4 deletions src/framing.c
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Original file line number Diff line number Diff line change
Expand Up @@ -60,17 +60,17 @@ ogg_int64_t ogg_page_granulepos(const ogg_page *og){
}

int ogg_page_serialno(const ogg_page *og){
return((int)((ogg_uint32_t)og->header[14]) |
return((int)(((ogg_uint32_t)og->header[14]) |
((ogg_uint32_t)og->header[15]<<8) |
((ogg_uint32_t)og->header[16]<<16) |
((ogg_uint32_t)og->header[17]<<24));
((ogg_uint32_t)og->header[17]<<24)));
}

long ogg_page_pageno(const ogg_page *og){
return((long)((ogg_uint32_t)og->header[18]) |
return((long)(((ogg_uint32_t)og->header[18]) |
((ogg_uint32_t)og->header[19]<<8) |
((ogg_uint32_t)og->header[20]<<16) |
((ogg_uint32_t)og->header[21]<<24));
((ogg_uint32_t)og->header[21]<<24)));
}


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