linux-kernel - [PATCH 2/3] perf symbols: Fix unaligned access in get_x86_64_plt

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Date:   Thu, 16 Mar 2023 21:41:55 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: [PATCH 2/3] perf symbols: Fix unaligned access in get_x86_64_plt_disp()

Use memcpy() to avoid unaligned access.

Discovered using EXTRA_CFLAGS="-fsanitize=undefined -fsanitize=address".

Reported-by: kernel test robot <yujie.liu@...el.com>
Link: https://lore.kernel.org/oe-lkp/202303061424.6ad43294-yujie.liu@intel.com
Fixes: ce4c8e7966f3 ("perf symbols: Get symbols for .plt.got for x86-64")
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/symbol-elf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 7ef5f6d7d415..ae810d4cf3cd 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -542,9 +542,12 @@ static u32 get_x86_64_plt_disp(const u8 *p)
 		n += 1;
 	/* jmp with 4-byte displacement */
 	if (p[n] == 0xff && p[n + 1] == 0x25) {
+		u32 disp;
+
 		n += 2;
 		/* Also add offset from start of entry to end of instruction */
-		return n + 4 + le32toh(*(const u32 *)(p + n));
+		memcpy(&disp, p + n, sizeof(disp));
+		return n + 4 + le32toh(disp);
 	}
 	return 0;
 }
-- 
2.34.1