linux-kernel - [PATCH 3.16 61/61] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core

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Message-ID: <lsq.1591725832.570281262@decadent.org.uk>
Date:   Tue, 09 Jun 2020 19:04:52 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Al Viro" <viro@...iv.linux.org.uk>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Alexey Dobriyan" <adobriyan@...il.com>,
        "Kees Cook" <keescook@...omium.org>,
        "Alexander Potapenko" <glider@...gle.com>,
        "sam" <sunhaoyl@...look.com>
Subject: [PATCH 3.16 61/61] fs/binfmt_elf.c: allocate initialized memory
 in fill_thread_core_info()

3.16.85-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Potapenko <glider@...gle.com>

commit 1d605416fb7175e1adf094251466caa52093b413 upstream.

KMSAN reported uninitialized data being written to disk when dumping
core.  As a result, several kilobytes of kmalloc memory may be written
to the core file and then read by a non-privileged user.

Reported-by: sam <sunhaoyl@...look.com>
Signed-off-by: Alexander Potapenko <glider@...gle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Acked-by: Kees Cook <keescook@...omium.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Link: http://lkml.kernel.org/r/20200419100848.63472-1-glider@google.com
Link: https://github.com/google/kmsan/issues/76
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/binfmt_elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1575,7 +1575,7 @@ static int fill_thread_core_info(struct
 		    (!regset->active || regset->active(t->task, regset) > 0)) {
 			int ret;
 			size_t size = regset->n * regset->size;
-			void *data = kmalloc(size, GFP_KERNEL);
+			void *data = kzalloc(size, GFP_KERNEL);
 			if (unlikely(!data))
 				return 0;
 			ret = regset->get(t->task, regset,