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author | Alexey Izbyshev <izbyshev@ispras.ru> | 2023-01-28 00:17:37 +0300 |
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committer | Rich Felker <dalias@aerifal.cx> | 2023-02-27 10:01:29 -0500 |
commit | 12590c8bbd04ea484cee86812e2258fbdfca0e59 (patch) | |
tree | 5f844f3a3ff128794c4bcc0cd73de2f3fadd3a61 /src/network/dns_parse.c | |
parent | bc695a5ac1d7929e5c1ad5297eb47e146cccd157 (diff) | |
download | musl-12590c8bbd04ea484cee86812e2258fbdfca0e59.tar.gz musl-12590c8bbd04ea484cee86812e2258fbdfca0e59.tar.bz2 musl-12590c8bbd04ea484cee86812e2258fbdfca0e59.tar.xz musl-12590c8bbd04ea484cee86812e2258fbdfca0e59.zip |
fix out-of-bounds reads in __dns_parse
There are several issues with range checks in this function:
* The question section parsing loop can read up to two out-of-bounds
bytes before doing the range check and bailing out.
* The answer section parsing loop, in addition to the same issue as
above, uses the wrong length in the range check that doesn't prevent
OOB reads when computing len later.
* The len range check before calling the callback is off by 10. Also,
p+len can overflow in a (probably theoretical) case when p is within
2^16 from UINTPTR_MAX.
Because __dns_parse is used only with stack-allocated buffers, such
small overreads can't result in a segfault. The first two also don't
affect the function result, but the last one may result in getaddrinfo
incorrectly succeeding and returning up to 10 bytes past the
response buffer as a part of the IP address, and in (canon) name
returned by getaddrinfo/getnameinfo being affected by memory past the
response buffer (because dn_expand might interpret it as a pointer).
Diffstat (limited to 'src/network/dns_parse.c')
-rw-r--r-- | src/network/dns_parse.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/network/dns_parse.c b/src/network/dns_parse.c index e6ee19d9..320df60d 100644 --- a/src/network/dns_parse.c +++ b/src/network/dns_parse.c @@ -15,17 +15,17 @@ int __dns_parse(const unsigned char *r, int rlen, int (*callback)(void *, int, c if (qdcount+ancount > 64) return -1; while (qdcount--) { while (p-r < rlen && *p-1U < 127) p++; - if (*p>193 || (*p==193 && p[1]>254) || p>r+rlen-6) + if (p>r+rlen-6 || *p>193 || (*p==193 && p[1]>254)) return -1; p += 5 + !!*p; } while (ancount--) { while (p-r < rlen && *p-1U < 127) p++; - if (*p>193 || (*p==193 && p[1]>254) || p>r+rlen-6) + if (p>r+rlen-12 || *p>193 || (*p==193 && p[1]>254)) return -1; p += 1 + !!*p; len = p[8]*256 + p[9]; - if (p+len > r+rlen) return -1; + if (len+10 > r+rlen-p) return -1; if (callback(ctx, p[1], p+10, len, r) < 0) return -1; p += 10 + len; } |