From f311c83a56beef14c079d5f28b745af07a146cc9 Mon Sep 17 00:00:00 2001 From: GNU Libc Maintainers Date: Sat, 16 Dec 2017 14:37:43 +0000 Subject: [PATCH] submitted-resolv-unaligned Gbp-Pq: Topic any Gbp-Pq: Name submitted-resolv-unaligned.diff --- resolv/res_mkquery.c | 9 +++++++++ resolv/res_query.c | 18 +++++++++++++----- resolv/res_send.c | 9 +++++++++ 3 files changed, 31 insertions(+), 5 deletions(-) diff --git a/resolv/res_mkquery.c b/resolv/res_mkquery.c index 5a0bb1044..9a457e35b 100644 --- a/resolv/res_mkquery.c +++ b/resolv/res_mkquery.c @@ -83,6 +83,15 @@ # define RANDOM_BITS(Var) { uint64_t v64; HP_TIMING_NOW (v64); Var = v64; } #endif +/* The structure HEADER is normally aligned to a word boundary and its + fields are accessed using word loads and stores. We need to access + this structure when it is aligned on a byte boundary. This can cause + problems on machines with strict alignment. So, we create a new + typedef to reduce its alignment to one. This ensures the fields are + accessed with byte loads and stores. */ +typedef HEADER __attribute__ ((__aligned__(1))) UHEADER; +#define HEADER UHEADER + /* * Form all types of queries. * Returns the size of the result or -1. diff --git a/resolv/res_query.c b/resolv/res_query.c index 57156d01e..51e6b8b2a 100644 --- a/resolv/res_query.c +++ b/resolv/res_query.c @@ -82,6 +82,14 @@ /* Options. Leave them on. */ /* #undef DEBUG */ +/* The structure HEADER is normally aligned to a word boundary and its + fields are accessed using word loads and stores. We need to access + this structure when it is aligned on a byte boundary. This can cause + problems on machines with strict alignment. So, we create a new + typedef to reduce its alignment to one. This ensures the fields are + accessed with byte loads and stores. */ +typedef HEADER __attribute__ ((__aligned__(1))) UHEADER; + #if PACKETSZ > 65536 #define MAXPACKET PACKETSZ #else @@ -118,8 +126,8 @@ __libc_res_nquery(res_state statp, int *resplen2, int *answerp2_malloced) { - HEADER *hp = (HEADER *) answer; - HEADER *hp2; + UHEADER *hp = (UHEADER *) answer; + UHEADER *hp2; int n, use_malloc = 0; u_int oflags = statp->_flags; @@ -250,7 +258,7 @@ __libc_res_nquery(res_state statp, if (answerp != NULL) /* __libc_res_nsend might have reallocated the buffer. */ - hp = (HEADER *) *answerp; + hp = (UHEADER *) *answerp; /* We simplify the following tests by assigning HP to HP2 or vice versa. It is easy to verify that this is the same as @@ -261,7 +269,7 @@ __libc_res_nquery(res_state statp, } else { - hp2 = (HEADER *) *answerp2; + hp2 = (UHEADER *) *answerp2; if (n < (int) sizeof (HEADER)) { hp = hp2; @@ -351,7 +359,7 @@ __libc_res_nsearch(res_state statp, int *answerp2_malloced) { const char *cp, * const *domain; - HEADER *hp = (HEADER *) answer; + UHEADER *hp = (UHEADER *) answer; char tmp[NS_MAXDNAME]; u_int dots; int trailing_dot, ret, saved_herrno; diff --git a/resolv/res_send.c b/resolv/res_send.c index 93db5b9a6..36a389509 100644 --- a/resolv/res_send.c +++ b/resolv/res_send.c @@ -110,6 +110,15 @@ #include #include +/* The structure HEADER is normally aligned to a word boundary and its + fields are accessed using word loads and stores. We need to access + this structure when it is aligned on a byte boundary. This can cause + problems on machines with strict alignment. So, we create a new + typedef to reduce its alignment to one. This ensures the fields are + accessed with byte loads and stores. */ +typedef HEADER __attribute__ ((__aligned__(1))) UHEADER; +#define HEADER UHEADER + #if PACKETSZ > 65536 #define MAXPACKET PACKETSZ #else -- 2.30.2