Package: yara Followup-For: Bug #869777 User: ubuntu-de...@lists.ubuntu.com Usertags: origin-ubuntu bionic ubuntu-patch
Hi Hilko, I've applied the following patch to yara in Ubuntu which fixes the non-portable alignment assumptions. This should be reasonably performant with modern gcc on supported architectures, and on some architectures will likely improve performance by eliminating unaligned accesses that are supported but costly to fix up. (This includes ARM in some configurations, since it's possible for unaligned access to not raise SIGBUS but still be an expensive operation.) Please consider applying this patch in Debian. Thanks, -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ slanga...@ubuntu.com vor...@debian.org
diff -Nru yara-3.7.1/debian/patches/no-unaligned-access.patch yara-3.7.1/debian/patches/no-unaligned-access.patch --- yara-3.7.1/debian/patches/no-unaligned-access.patch 1969-12-31 16:00:00.000000000 -0800 +++ yara-3.7.1/debian/patches/no-unaligned-access.patch 2018-02-04 14:08:33.000000000 -0800 @@ -0,0 +1,118 @@ +Description: use alignment-safe handling + Casting a char* to a uint64_t* is not universally safe due to alignment + constraints on reads on some platforms. Just use memcpy() instead, which + the compiler should optimize adequately for us. + . + Also, force alignment of our arena-allocated structures that contain 64-bit + elements. +Author: Steve Langasek <steve.langa...@ubuntu.com> + +Index: yara-3.7.1/libyara/exec.c +=================================================================== +--- yara-3.7.1.orig/libyara/exec.c ++++ yara-3.7.1/libyara/exec.c +@@ -227,7 +227,7 @@ + break; + + case OP_PUSH: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + push(r1); + break; +@@ -237,13 +237,13 @@ + break; + + case OP_CLEAR_M: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + mem[r1.i] = 0; + break; + + case OP_ADD_M: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + pop(r2); + if (!is_undef(r2)) +@@ -251,27 +251,27 @@ + break; + + case OP_INCR_M: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + mem[r1.i]++; + break; + + case OP_PUSH_M: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + r1.i = mem[r1.i]; + push(r1); + break; + + case OP_POP_M: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + pop(r2); + mem[r1.i] = r2.i; + break; + + case OP_SWAPUNDEF: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + pop(r2); + +@@ -859,7 +859,7 @@ + break; + + case OP_IMPORT: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + + result = yr_modules_load((char*) r1.p, context); +@@ -902,7 +902,7 @@ + break; + + case OP_INT_TO_DBL: +- r1.i = *(uint64_t*)(ip); ++ memcpy(&r1.i, ip, sizeof(uint64_t)); + ip += sizeof(uint64_t); + r2 = stack[sp - r1.i]; + if (is_undef(r2)) +Index: yara-3.7.1/libyara/scan.c +=================================================================== +--- yara-3.7.1.orig/libyara/scan.c ++++ yara-3.7.1/libyara/scan.c +@@ -397,8 +397,11 @@ + + FAIL_ON_ERROR(yr_arena_allocate_memory( + context->matches_arena, +- sizeof(YR_MATCH), ++ sizeof(YR_MATCH) + sizeof(uint64_t) - 1, + (void**) &new_match)); ++ /* force alignment */ ++ new_match = (YR_MATCH *)(((size_t)new_match + sizeof(uint64_t) - 1) ++ & ~(sizeof(uint64_t) - 1)); + + new_match->data_length = yr_min(match_length, MAX_MATCH_DATA); + +@@ -500,8 +503,11 @@ + + FAIL_ON_ERROR(yr_arena_allocate_memory( + callback_args->context->matches_arena, +- sizeof(YR_MATCH), ++ sizeof(YR_MATCH) + sizeof(uint64_t) - 1, + (void**) &new_match)); ++ /* force alignment */ ++ new_match = (YR_MATCH *)(((size_t)new_match + sizeof(uint64_t) - 1) ++ & ~(sizeof(uint64_t) - 1)); + + new_match->data_length = yr_min(match_length, MAX_MATCH_DATA); + diff -Nru yara-3.7.1/debian/patches/series yara-3.7.1/debian/patches/series --- yara-3.7.1/debian/patches/series 2018-01-16 04:45:26.000000000 -0800 +++ yara-3.7.1/debian/patches/series 2018-02-04 14:04:53.000000000 -0800 @@ -1 +1,2 @@ 0001-Use-Linux-style-procfs-on-kFreeBSD-because-struct-pt.patch +no-unaligned-access.patch
