Message ID | 27360402.O0bhZDOYKm@pygoscelis |
---|---|
State | Superseded, archived |
Headers | show |
Series | [pacman-dev,1/1] Fix CVE-2016-5434 (DoS/loop and out of boundary read) | expand |
This is an update to fix style issues (indentation, newlines etc.) that were addressed on IRC. Original message: >This is a rewrite of Tobias Stoeckmann’s patch from June 2016[1] using >functions instead of macros. (Thanks to Tobias for explanations of his patch.) >A short question on Freenode IRC showed that macros are generally discouraged >and functions should be used. > >The patch introduces size_t length_check() and applies it to >libalpm/signing.c and signing.h. > >Feedback is very appreciated. > > >[1] Original patch: >https://lists.archlinux.org/pipermail/pacman-dev/2016-June/021148.html >CVE request (and assignment): >http://seclists.org/oss-sec/2016/q2/526 diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c index 95cb3280..3a907bb8 100644 --- a/lib/libalpm/signing.c +++ b/lib/libalpm/signing.c @@ -986,6 +986,19 @@ int SYMEXPORT alpm_siglist_cleanup(alpm_siglist_t *siglist) return 0; } +/* Check to avoid out of boundary reads */ +size_t length_check(size_t length, size_t position, size_t a, + alpm_handle_t *handle, const char *identifier) +{ + if( a == 0 || length - position <= a) { + _alpm_log(handle, ALPM_LOG_ERROR, + _("%s: signature format error"), identifier); + return -1; + } else { + return 0; + } +} + /** * Extract the Issuer Key ID from a signature * @param sig PGP signature @@ -1022,18 +1035,41 @@ int SYMEXPORT alpm_extract_keyid(alpm_handle_t *handle, const char *identifier, switch(sig[pos] & 0x03) { case 0: - blen = sig[pos + 1]; - pos = pos + 2; + if(length_check(len, pos, 1, handle, identifier)) { + return -1; + } else { + blen = sig[pos + 1]; + } + if(length_check(len, pos, 2, handle, identifier)) { + return -1; + } else { + pos = pos + 2; + } break; - case 1: - blen = (sig[pos + 1] << 8) | sig[pos + 2]; - pos = pos + 3; + if(length_check(len, pos, 2, handle, identifier)) { + return -1; + } else { + blen = (sig[pos + 1] << 8) | sig[pos + 2]; + } + if(length_check(len, pos, 3, handle, identifier)) { + return -1; + } else { + pos = pos + 3; + } break; case 2: - blen = (sig[pos + 1] << 24) | (sig[pos + 2] << 16) | (sig[pos + 3] << 8) | sig[pos + 4]; - pos = pos + 5; + if(length_check(len, pos, 4, handle, identifier)) { + return -1; + } else { + blen = (sig[pos + 1] << 24) | (sig[pos + 2] << 16) | (sig[pos + 3] << 8) | sig[pos + 4]; + } + if(length_check(len, pos, 5, handle, identifier)) { + return -1; + } else { + pos = pos + 5; + } break; case 3: @@ -1057,43 +1093,99 @@ int SYMEXPORT alpm_extract_keyid(alpm_handle_t *handle, const char *identifier, return -1; } - pos = pos + 4; + if(length_check(len, pos, 4, handle, identifier)) { + return -1; + } else { + pos = pos + 4; + } - hlen = (sig[pos] << 8) | sig[pos + 1]; - pos = pos + hlen + 2; + if(length_check(len, pos, 1, handle, identifier)) { + return -1; + } else { + hlen = (sig[pos] << 8) | sig[pos + 1]; + } - ulen = (sig[pos] << 8) | sig[pos + 1]; - pos = pos + 2; + if(length_check(len, pos, 2, handle, identifier)) { + return -1; + } else { + pos = pos + hlen + 2; + } - spos = pos; + if(length_check(len, pos, 1, handle, identifier)) { + return -1; + } else { + ulen = (sig[pos] << 8) | sig[pos + 1]; + } - while(spos < pos + ulen) { - if(sig[spos] < 192) { - slen = sig[spos]; - spos = spos + 1; - } else if(sig[spos] < 255) { - slen = (sig[spos] << 8) | sig[spos + 1]; - spos = spos + 2; - } else { - slen = (sig[spos + 1] << 24) | (sig[spos + 2] << 16) | (sig[spos + 3] << 8) | sig[spos + 4]; - spos = spos + 5; - } + if(length_check(len, pos, 2, handle, identifier)) { + return -1; + } else { + pos = pos + 2; + } - if(sig[spos] == 16) { - /* issuer key ID */ - char key[17]; - size_t i; - for (i = 0; i < 8; i++) { - sprintf(&key[i * 2], "%02X", sig[spos + i + 1]); + spos = pos; + + if(length_check(len, pos, ulen, handle, identifier)) { + return -1; + } else { + while(spos < pos + ulen) { + if(sig[spos] < 192) { + slen = sig[spos]; + if(length_check(len + ulen, spos, 1, handle, identifier)) { + return -1; + } else { + spos = spos + 1; + } + } else if(sig[spos] < 255) { + if(length_check(pos + ulen, spos, 1, handle, identifier)) + { + return -1; + } else { + slen = (sig[spos] << 8) | sig[spos + 1]; + } + if(length_check(pos + ulen, spos, 2, handle, identifier)) { + return -1; + } else { + spos = spos + 2; + } + } else { + if(length_check(len, pos, 4, handle, identifier)) { + return -1; + } else { + slen = (sig[spos + 1] << 24) | (sig[spos + 2] << 16) | (sig[spos + 3] << 8) | sig[spos + 4]; + } + if(length_check(len, spos, 5, handle, identifier)) { + return -1; + } else { + spos = spos + 5; + } + } + if(sig[spos] == 16) { + /* issuer key ID */ + char key[17]; + size_t i; + if(length_check(pos + ulen, spos, 8, handle, identifier)) { + return -1; + } else { + for (i = 0; i < 8; i++) { + sprintf(&key[i * 2], "%02X", sig[spos + i + 1]); + } + } + *keys = alpm_list_add(*keys, strdup(key)); + break; + } + if(length_check(pos + ulen + 1, spos, slen, handle, identifier)) { + return -1; + } else { + spos = spos + slen; } - *keys = alpm_list_add(*keys, strdup(key)); - break; } - - spos = spos + slen; + if(length_check( blen, hlen, 8, handle, identifier )) { + return -1; + } else { + pos = pos + (blen - hlen - 8); + } } - - pos = pos + (blen - hlen - 8); } return 0; diff --git a/lib/libalpm/signing.h b/lib/libalpm/signing.h index 3507f584..a67bd900 100644 --- a/lib/libalpm/signing.h +++ b/lib/libalpm/signing.h @@ -36,4 +36,6 @@ int _alpm_key_import(alpm_handle_t *handle, const char *fpr); #endif /* ALPM_SIGNING_H */ +size_t length_check(size_t length, size_t position, size_t a, + alpm_handle_t *handle, const char *identifier); /* vim: set noet: */
On 06/09/17 02:04, Nils Freydank wrote: > This is an update to fix style issues (indentation, newlines etc.) that were addressed on IRC. > > Original message: >> This is a rewrite of Tobias Stoeckmann’s patch from June 2016[1] using >> functions instead of macros. (Thanks to Tobias for explanations of his patch.) >> A short question on Freenode IRC showed that macros are generally discouraged >> and functions should be used. >> >> The patch introduces size_t length_check() and applies it to >> libalpm/signing.c and signing.h. >> >> Feedback is very appreciated. >> >> >> [1] Original patch: >> https://lists.archlinux.org/pipermail/pacman-dev/2016-June/021148.html >> CVE request (and assignment): >> http://seclists.org/oss-sec/2016/q2/526 > Please send as a git patch. > diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c > index 95cb3280..3a907bb8 100644 > --- a/lib/libalpm/signing.c > +++ b/lib/libalpm/signing.c > @@ -986,6 +986,19 @@ int SYMEXPORT alpm_siglist_cleanup(alpm_siglist_t *siglist) > return 0; > } > > +/* Check to avoid out of boundary reads */ This function is not used outside this file, so scope it there. If needed elsewhere, it can be moved to util.c. static size_t ... > +size_t length_check(size_t length, size_t position, size_t a, > + alpm_handle_t *handle, const char *identifier) > +{ > + if( a == 0 || length - position <= a) { > + _alpm_log(handle, ALPM_LOG_ERROR, > + _("%s: signature format error"), identifier); > + return -1; > + } else { > + return 0; > + } > +} > + > /** > * Extract the Issuer Key ID from a signature > * @param sig PGP signature > @@ -1022,18 +1035,41 @@ int SYMEXPORT alpm_extract_keyid(alpm_handle_t *handle, const char *identifier, > > switch(sig[pos] & 0x03) { > case 0: > - blen = sig[pos + 1]; > - pos = pos + 2; Too much going on here.... > + if(length_check(len, pos, 1, handle, identifier)) { > + return -1; > + } else { > + blen = sig[pos + 1]; > + } > + if(length_check(len, pos, 2, handle, identifier)) { > + return -1; > + } else { > + pos = pos + 2; > + } Replace this block with : if(length_check(len, pos, 2, handle, identifier) != 0) { return -1; } blen = sig[pos + 1]; pos = pos + 2; Note the explicit test of != 0 in the if statement. This combining of tests can be done throughout the patch. > break; > - > case 1: > - blen = (sig[pos + 1] << 8) | sig[pos + 2]; > - pos = pos + 3; > + if(length_check(len, pos, 2, handle, identifier)) { > + return -1; > + } else { > + blen = (sig[pos + 1] << 8) | sig[pos + 2]; > + } > + if(length_check(len, pos, 3, handle, identifier)) { > + return -1; > + } else { > + pos = pos + 3; > + } > break; > > case 2: > - blen = (sig[pos + 1] << 24) | (sig[pos + 2] << 16) | (sig[pos + 3] << 8) | sig[pos + 4]; > - pos = pos + 5; > + if(length_check(len, pos, 4, handle, identifier)) { > + return -1; > + } else { > + blen = (sig[pos + 1] << 24) | (sig[pos + 2] << 16) | (sig[pos + 3] << 8) | sig[pos + 4]; > + } > + if(length_check(len, pos, 5, handle, identifier)) { > + return -1; > + } else { > + pos = pos + 5; > + } > break; > > case 3: > @@ -1057,43 +1093,99 @@ int SYMEXPORT alpm_extract_keyid(alpm_handle_t *handle, const char *identifier, > return -1; > } > > - pos = pos + 4; > + if(length_check(len, pos, 4, handle, identifier)) { > + return -1; > + } else { > + pos = pos + 4; > + } > > - hlen = (sig[pos] << 8) | sig[pos + 1]; > - pos = pos + hlen + 2; > + if(length_check(len, pos, 1, handle, identifier)) { > + return -1; > + } else { > + hlen = (sig[pos] << 8) | sig[pos + 1]; > + } > > - ulen = (sig[pos] << 8) | sig[pos + 1]; > - pos = pos + 2; > + if(length_check(len, pos, 2, handle, identifier)) { > + return -1; > + } else { > + pos = pos + hlen + 2; > + } > > - spos = pos; > + if(length_check(len, pos, 1, handle, identifier)) { > + return -1; > + } else { > + ulen = (sig[pos] << 8) | sig[pos + 1]; > + } > > - while(spos < pos + ulen) { > - if(sig[spos] < 192) { > - slen = sig[spos]; > - spos = spos + 1; > - } else if(sig[spos] < 255) { > - slen = (sig[spos] << 8) | sig[spos + 1]; > - spos = spos + 2; > - } else { > - slen = (sig[spos + 1] << 24) | (sig[spos + 2] << 16) | (sig[spos + 3] << 8) | sig[spos + 4]; > - spos = spos + 5; > - } > + if(length_check(len, pos, 2, handle, identifier)) { > + return -1; > + } else { > + pos = pos + 2; > + } > > - if(sig[spos] == 16) { > - /* issuer key ID */ > - char key[17]; > - size_t i; > - for (i = 0; i < 8; i++) { > - sprintf(&key[i * 2], "%02X", sig[spos + i + 1]); > + spos = pos; > + > + if(length_check(len, pos, ulen, handle, identifier)) { > + return -1; > + } else { > + while(spos < pos + ulen) { > + if(sig[spos] < 192) { > + slen = sig[spos]; > + if(length_check(len + ulen, spos, 1, handle, identifier)) { > + return -1; > + } else { > + spos = spos + 1; > + } > + } else if(sig[spos] < 255) { > + if(length_check(pos + ulen, spos, 1, handle, identifier)) > + { > + return -1; > + } else { > + slen = (sig[spos] << 8) | sig[spos + 1]; > + } > + if(length_check(pos + ulen, spos, 2, handle, identifier)) { > + return -1; > + } else { > + spos = spos + 2; > + } > + } else { > + if(length_check(len, pos, 4, handle, identifier)) { > + return -1; > + } else { > + slen = (sig[spos + 1] << 24) | (sig[spos + 2] << 16) | (sig[spos + 3] << 8) | sig[spos + 4]; > + } > + if(length_check(len, spos, 5, handle, identifier)) { > + return -1; > + } else { > + spos = spos + 5; > + } > + } > + if(sig[spos] == 16) { > + /* issuer key ID */ > + char key[17]; > + size_t i; > + if(length_check(pos + ulen, spos, 8, handle, identifier)) { > + return -1; > + } else { > + for (i = 0; i < 8; i++) { > + sprintf(&key[i * 2], "%02X", sig[spos + i + 1]); > + } > + } > + *keys = alpm_list_add(*keys, strdup(key)); > + break; > + } > + if(length_check(pos + ulen + 1, spos, slen, handle, identifier)) { > + return -1; > + } else { > + spos = spos + slen; > } > - *keys = alpm_list_add(*keys, strdup(key)); > - break; > } > - > - spos = spos + slen; > + if(length_check( blen, hlen, 8, handle, identifier )) { > + return -1; > + } else { > + pos = pos + (blen - hlen - 8); > + } > } > - > - pos = pos + (blen - hlen - 8); > } > > return 0; Remove the header addition: > diff --git a/lib/libalpm/signing.h b/lib/libalpm/signing.h > index 3507f584..a67bd900 100644 > --- a/lib/libalpm/signing.h > +++ b/lib/libalpm/signing.h > @@ -36,4 +36,6 @@ int _alpm_key_import(alpm_handle_t *handle, const char *fpr); > > #endif /* ALPM_SIGNING_H */ > > +size_t length_check(size_t length, size_t position, size_t a, > + alpm_handle_t *handle, const char *identifier); > /* vim: set noet: */ >
diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c index 95cb3280..f7a9c9a8 100644 --- a/lib/libalpm/signing.c +++ b/lib/libalpm/signing.c @@ -986,6 +986,19 @@ int SYMEXPORT alpm_siglist_cleanup(alpm_siglist_t *siglist) return 0; } +/* Check to avoid out of boundary reads */ +size_t length_check(size_t length, size_t position, size_t a, + alpm_handle_t *handle, const char *identifier) +{ + if( a == 0 || length - position <= a) + { + _alpm_log(handle, ALPM_LOG_ERROR, \ + _("%s: signature format error"), identifier); + return -1; + } + else return 0; +} + /** * Extract the Issuer Key ID from a signature * @param sig PGP signature @@ -1021,19 +1034,22 @@ int SYMEXPORT alpm_extract_keyid(alpm_handle_t *handle, const char *identifier, } switch(sig[pos] & 0x03) { - case 0: - blen = sig[pos + 1]; - pos = pos + 2; + case 0: if( length_check(len, pos, 1, handle, identifier) ){ return -1; } + else blen = sig[pos + 1]; + if( length_check(len, pos, 2, handle, identifier) ){ return -1; } + else pos = pos + 2; break; - case 1: - blen = (sig[pos + 1] << 8) | sig[pos + 2]; - pos = pos + 3; + if( length_check(len, pos, 2, handle, identifier) ){ return -1; } + else blen = (sig[pos + 1] << 8) | sig[pos + 2]; + if( length_check(len, pos, 3, handle, identifier) ){ return -1; } + else pos = pos + 3; break; - case 2: - blen = (sig[pos + 1] << 24) | (sig[pos + 2] << 16) | (sig[pos + 3] << 8) | sig[pos + 4]; - pos = pos + 5; + case 2: if( length_check(len, pos, 4, handle, identifier) ){ return -1; } + else blen = (sig[pos + 1] << 24) | (sig[pos + 2] << 16) | (sig[pos + 3] << 8) | sig[pos + 4]; + if( length_check(len, pos, 5, handle, identifier) ){ return -1; } + else pos = pos + 5; break; case 3: @@ -1057,25 +1073,38 @@ int SYMEXPORT alpm_extract_keyid(alpm_handle_t *handle, const char *identifier, return -1; } - pos = pos + 4; + if( length_check(len, pos, 4, handle, identifier) ){ return -1; } + else pos = pos + 4; - hlen = (sig[pos] << 8) | sig[pos + 1]; - pos = pos + hlen + 2; + if( length_check(len, pos, 1, handle, identifier) ){ return -1; } + else hlen = (sig[pos] << 8) | sig[pos + 1]; - ulen = (sig[pos] << 8) | sig[pos + 1]; - pos = pos + 2; + if( length_check(len, pos, 2, handle, identifier) ){ return -1; } + else pos = pos + hlen + 2; + + if( length_check(len, pos, 1, handle, identifier) ){ return -1; } + else ulen = (sig[pos] << 8) | sig[pos + 1]; + + if( length_check(len, pos, 2, handle, identifier) ){ return -1; } + else pos = pos + 2; spos = pos; + if( length_check(len, pos, ulen, handle, identifier) ){ return -1; } + else while(spos < pos + ulen) { if(sig[spos] < 192) { slen = sig[spos]; - spos = spos + 1; + if( length_check(len + ulen, spos, 1, handle, identifier) ){ return -1; } + else spos = spos + 1; } else if(sig[spos] < 255) { - slen = (sig[spos] << 8) | sig[spos + 1]; - spos = spos + 2; + if( length_check(pos + ulen, spos, 1, handle, identifier) ){ return -1; } + else slen = (sig[spos] << 8) | sig[spos + 1]; + if( length_check(pos + ulen, spos, 2, handle, identifier) ){ return -1; } + else spos = spos + 2; } else { - slen = (sig[spos + 1] << 24) | (sig[spos + 2] << 16) | (sig[spos + 3] << 8) | sig[spos + 4]; + if( length_check(len, pos, 4, handle, identifier) ){ return -1; } + else slen = (sig[spos + 1] << 24) | (sig[spos + 2] << 16) | (sig[spos + 3] << 8) | sig[spos + 4]; spos = spos + 5; } @@ -1083,17 +1112,20 @@ int SYMEXPORT alpm_extract_keyid(alpm_handle_t *handle, const char *identifier, /* issuer key ID */ char key[17]; size_t i; + if( length_check(pos + ulen, spos, 8, handle, identifier) ){return -1; } + else{ for (i = 0; i < 8; i++) { sprintf(&key[i * 2], "%02X", sig[spos + i + 1]); } + } *keys = alpm_list_add(*keys, strdup(key)); break; } - - spos = spos + slen; + if( length_check(pos + ulen + 1, spos, slen, handle, identifier) ) {return -1; } + else spos = spos + slen; } - - pos = pos + (blen - hlen - 8); + if( length_check( blen, hlen, 8, handle, identifier ) ){return -1;} + else pos = pos + (blen - hlen - 8); } return 0; diff --git a/lib/libalpm/signing.h b/lib/libalpm/signing.h index 3507f584..a67bd900 100644 --- a/lib/libalpm/signing.h +++ b/lib/libalpm/signing.h @@ -36,4 +36,6 @@ int _alpm_key_import(alpm_handle_t *handle, const char *fpr); #endif /* ALPM_SIGNING_H */ +size_t length_check(size_t length, size_t position, size_t a, + alpm_handle_t *handle, const char *identifier);