[sr-dev] [kamailio] Fix read buffer overflow in parse_hname2 (#308)

Fix buffer overflow in READ call by making a SAFE_READ that checks the actual length of the buffer. In the buffer overflow case parse_hname2 is called with 'begin' set to the string "Reason:". This string was originally allocated in in rval_get_str as length 6, contents "Reason\0'. The actual pkg_malloc is size of 7 to account for the null terminator. In the caller to parse_hname2 (modules/textops/textops.c line 2229) the null terminator is replaced with a ':' character. parse_hname2 hits the FIRST_QUARTERNIONS macro which expands to a bunch of case statements. The one for the Reason string looks like (macro expanded): case _reas_: p += 4; val = READ(p); switch(LOWER_DWORD(val)) { case _on1_: hdr->type = HDR_REASON_T; hdr->name.len = 6; return (p + 3); The overflow occurs in the READ call. READ is: (*(val + 0) + (*(val + 1) << 8) + (*(val + 2) << 16) + (*(val + 3) << 24)) With 'p' pointing to "Reason:", then p+4 is "on:". That's only three characters of allocated memory left(the : was originally the null character as explained above and the total pkg_malloc allocated length was 7). READ accesses 4 bytes so we go one past the end of the allocated area. The error is noticeable in a DBG_SYS_MALLOC build but not a PKG_MALLOC build - I assume the latter has a large arena allocated making the buffer overflow still valid memory. There are likely other buffer overflows in the READ usage in other cases in this function. I've [posted to the mailing list](http://lists.sip-router.org/pipermail/sr-dev/2015-August/030529.html) about the issue and whether a more general fix is possible: You can view, comment on, or merge this pull request online at: https://github.com/kamailio/kamailio/pull/308 -- Commit Summary -- * Fix read buffer overflow in parse_hname2 -- File Changes -- M parser/case_reas.h (2) M parser/parse_hname2.c (19) -- Patch Links -- https://github.com/kamailio/kamailio/pull/308.patch https://github.com/kamailio/kamailio/pull/308.diff --- Reply to this email directly or view it on GitHub: https://github.com/kamailio/kamailio/pull/308