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| author | Alexey Izbyshev <izbyshev@ispras.ru> | 2023-01-29 19:46:51 +0300 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2023-02-27 10:03:06 -0500 |
| commit | 9b132e556774c744f9052581d2d8d0fab417e97c (patch) | |
| tree | cbb516502c92f69bb6b01c82dbb7c30fed845c56 | |
| parent | 12590c8bbd04ea484cee86812e2258fbdfca0e59 (diff) | |
| download | musl-9b132e556774c744f9052581d2d8d0fab417e97c.tar.gz musl-9b132e556774c744f9052581d2d8d0fab417e97c.tar.xz musl-9b132e556774c744f9052581d2d8d0fab417e97c.zip | |
prevent CNAME/PTR parsing from reading data past the response end
DNS parsing callbacks pass the response buffer end instead of the actual response end to dn_expand, so a malformed DNS response can use message compression to make dn_expand jump past the response end and attempt to parse uninitialized parts of that buffer, which might succeed and return garbage.
| -rw-r--r-- | src/network/dns_parse.c | 4 | ||||
| -rw-r--r-- | src/network/getnameinfo.c | 4 | ||||
| -rw-r--r-- | src/network/lookup.h | 2 | ||||
| -rw-r--r-- | src/network/lookup_name.c | 4 |
4 files changed, 7 insertions, 7 deletions
diff --git a/src/network/dns_parse.c b/src/network/dns_parse.c index 320df60d..7f83e791 100644 --- a/src/network/dns_parse.c +++ b/src/network/dns_parse.c @@ -1,7 +1,7 @@ #include <string.h> #include "lookup.h" -int __dns_parse(const unsigned char *r, int rlen, int (*callback)(void *, int, const void *, int, const void *), void *ctx) +int __dns_parse(const unsigned char *r, int rlen, int (*callback)(void *, int, const void *, int, const void *, int), void *ctx) { int qdcount, ancount; const unsigned char *p; @@ -26,7 +26,7 @@ int __dns_parse(const unsigned char *r, int rlen, int (*callback)(void *, int, c p += 1 + !!*p; len = p[8]*256 + p[9]; if (len+10 > r+rlen-p) return -1; - if (callback(ctx, p[1], p+10, len, r) < 0) return -1; + if (callback(ctx, p[1], p+10, len, r, rlen) < 0) return -1; p += 10 + len; } return 0; diff --git a/src/network/getnameinfo.c b/src/network/getnameinfo.c index 949e1811..080d3c06 100644 --- a/src/network/getnameinfo.c +++ b/src/network/getnameinfo.c @@ -108,10 +108,10 @@ static void reverse_services(char *buf, int port, int dgram) __fclose_ca(f); } -static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet) +static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet, int plen) { if (rr != RR_PTR) return 0; - if (__dn_expand(packet, (const unsigned char *)packet + 512, + if (__dn_expand(packet, (const unsigned char *)packet + plen, data, c, 256) <= 0) *(char *)c = 0; return 0; diff --git a/src/network/lookup.h b/src/network/lookup.h index ef662725..54b2f8b5 100644 --- a/src/network/lookup.h +++ b/src/network/lookup.h @@ -50,6 +50,6 @@ hidden int __lookup_ipliteral(struct address buf[static 1], const char *name, in hidden int __get_resolv_conf(struct resolvconf *, char *, size_t); hidden int __res_msend_rc(int, const unsigned char *const *, const int *, unsigned char *const *, int *, int, const struct resolvconf *); -hidden int __dns_parse(const unsigned char *, int, int (*)(void *, int, const void *, int, const void *), void *); +hidden int __dns_parse(const unsigned char *, int, int (*)(void *, int, const void *, int, const void *, int), void *); #endif diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c index 5f6867cb..f268bcda 100644 --- a/src/network/lookup_name.c +++ b/src/network/lookup_name.c @@ -111,13 +111,13 @@ struct dpc_ctx { #define ABUF_SIZE 768 -static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet) +static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet, int plen) { char tmp[256]; int family; struct dpc_ctx *ctx = c; if (rr == RR_CNAME) { - if (__dn_expand(packet, (const unsigned char *)packet + ABUF_SIZE, + if (__dn_expand(packet, (const unsigned char *)packet + plen, data, tmp, sizeof tmp) > 0 && is_valid_hostname(tmp)) strcpy(ctx->canon, tmp); return 0; |