From 1a51c85b7a856616d14028abb794c8d80da0c110 Mon Sep 17 00:00:00 2001 From: Ubuntu Developers Date: Fri, 13 May 2022 23:32:11 +0800 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 62beb24c..1bdf6bab 100644 --- a/resolv/res_mkquery.c +++ b/resolv/res_mkquery.c @@ -95,6 +95,15 @@ #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 + int __res_context_mkquery (struct resolv_context *ctx, int op, const char *dname, int class, int type, const unsigned char *data, diff --git a/resolv/res_query.c b/resolv/res_query.c index ebbe5a6a..3e0b3291 100644 --- a/resolv/res_query.c +++ b/resolv/res_query.c @@ -81,6 +81,14 @@ #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; + #if PACKETSZ > 65536 #define MAXPACKET PACKETSZ #else @@ -112,8 +120,8 @@ __res_context_query (struct resolv_context *ctx, const char *name, int *nanswerp2, int *resplen2, int *answerp2_malloced) { struct __res_state *statp = ctx->resp; - HEADER *hp = (HEADER *) answer; - HEADER *hp2; + UHEADER *hp = (UHEADER *) answer; + UHEADER *hp2; int n, use_malloc = 0; size_t bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * QUERYSIZE; @@ -217,7 +225,7 @@ __res_context_query (struct resolv_context *ctx, const char *name, if (answerp != NULL) /* __res_context_send 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 @@ -228,7 +236,7 @@ __res_context_query (struct resolv_context *ctx, const char *name, } else { - hp2 = (HEADER *) *answerp2; + hp2 = (UHEADER *) *answerp2; if (n < (int) sizeof (HEADER)) { hp = hp2; @@ -327,7 +335,7 @@ __res_context_search (struct resolv_context *ctx, { struct __res_state *statp = ctx->resp; const char *cp; - 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 7e5fec66..65af6a1e 100644 --- a/resolv/res_send.c +++ b/resolv/res_send.c @@ -111,6 +111,15 @@ #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