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mod_mime_magic: reject negative indirect offset in mget #715

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mod_mime_magic: reject negative indirect offset in mget #715

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3 changes: 3 additions & 0 deletions changes-entries/mime-magic-negative-offset.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
*) mod_mime_magic: Reject negative indirect offsets in mget() so a crafted
file cannot drive an out-of-bounds read of the sniff buffer.
[arshiya tabasum]
4 changes: 2 additions & 2 deletions modules/metadata/mod_mime_magic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1814,7 +1814,7 @@ static int mget(request_rec *r, union VALUETYPE *p, unsigned char *s,
{
long offset = m->offset;

if (offset + sizeof(union VALUETYPE) > nbytes)
if (offset < 0 || (apr_size_t)offset + sizeof(union VALUETYPE) > nbytes)
return 0;

memcpy(p, s + offset, sizeof(union VALUETYPE));
Expand All @@ -1836,7 +1836,7 @@ static int mget(request_rec *r, union VALUETYPE *p, unsigned char *s,
break;
}

if (offset + sizeof(union VALUETYPE) > nbytes)
if (offset < 0 || (apr_size_t)offset + sizeof(union VALUETYPE) > nbytes)
return 0;

memcpy(p, s + offset, sizeof(union VALUETYPE));
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