From fc039ce8502d236f11074eb58468be24b4fa8cc7 Mon Sep 17 00:00:00 2001 From: Ludwig Rydberg Date: Mon, 11 Dec 2023 13:50:41 +0100 Subject: resolv: Fix a few unaligned accesses to fields in HEADER After refactoring the alloca usage in 40c0add7d4 ("resolve: Remove __res_context_query alloca usage") a few unaligned accesses to HEADER fields surfaced. These unaligned accesses led to problems when running the resolv test suite on sparc32-linux (leon) as many tests failed due to SIGBUS crashes. The issue(s) occured during T_QUERY_A_AND_AAAA queries as the second query now can start on an unaligned address (previously it was explicitly aligned). With this patch the unaligned accesses are now fixed by using the UHEADER instead to ensure the fields are accessed with byte loads/stores. The patch has been verfied by running the resolv test suite on sparc32 and x86_64. Signed-off-by: Ludwig Rydberg Signed-off-by: Andreas Larsson Reviewed-by: Florian Weimer --- resolv/res_mkquery.c | 6 +++--- resolv/res_queriesmatch.c | 6 +++--- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/resolv/res_mkquery.c b/resolv/res_mkquery.c index e9316b3..a46a924 100644 --- a/resolv/res_mkquery.c +++ b/resolv/res_mkquery.c @@ -100,7 +100,7 @@ __res_context_mkquery (struct resolv_context *ctx, int op, const char *dname, int class, int type, const unsigned char *data, unsigned char *buf, int buflen) { - HEADER *hp; + UHEADER *hp; unsigned char *cp; int n; unsigned char *dnptrs[20], **dpp, **lastdnptr; @@ -112,7 +112,7 @@ __res_context_mkquery (struct resolv_context *ctx, int op, const char *dname, if ((buf == NULL) || (buflen < HFIXEDSZ)) return -1; memset (buf, 0, HFIXEDSZ); - hp = (HEADER *) buf; + hp = (UHEADER *) buf; /* We randomize the IDs every time. The old code just incremented by one after the initial randomization which still predictable if the application does multiple requests. */ @@ -250,7 +250,7 @@ __res_nopt (struct resolv_context *ctx, int n0, unsigned char *buf, int buflen, int anslen) { uint16_t flags = 0; - HEADER *hp = (HEADER *) buf; + UHEADER *hp = (UHEADER *) buf; unsigned char *cp = buf + n0; unsigned char *ep = buf + buflen; diff --git a/resolv/res_queriesmatch.c b/resolv/res_queriesmatch.c index ba1c1d0..37db01a 100644 --- a/resolv/res_queriesmatch.c +++ b/resolv/res_queriesmatch.c @@ -95,14 +95,14 @@ __libc_res_queriesmatch (const unsigned char *buf1, const unsigned char *eom1, /* Only header section present in replies to dynamic update packets. */ - if ((((HEADER *) buf1)->opcode == ns_o_update) && - (((HEADER *) buf2)->opcode == ns_o_update)) + if ((((UHEADER *) buf1)->opcode == ns_o_update) && + (((UHEADER *) buf2)->opcode == ns_o_update)) return 1; /* Note that we initially do not convert QDCOUNT to the host byte order. We can compare it with the second buffer's QDCOUNT value without doing this. */ - int qdcount = ((HEADER *) buf1)->qdcount; + int qdcount = ((UHEADER *) buf1)->qdcount; if (qdcount != ((UHEADER *) buf2)->qdcount) return 0; -- cgit v1.1