linux-kernel - [PATCH 5.6 134/177] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core

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Date:   Mon,  1 Jun 2020 19:54:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, sam <sunhaoyl@...look.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.6 134/177] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info()

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

[ Upstream commit 1d605416fb7175e1adf094251466caa52093b413 ]

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>
Cc: <stable@...r.kernel.org>
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>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/binfmt_elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index f4713ea76e82..54f888ddb8cc 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1733,7 +1733,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 		    (!regset->active || regset->active(t->task, regset) > 0)) {
 			int ret;
 			size_t size = regset_size(t->task, regset);
-			void *data = kmalloc(size, GFP_KERNEL);
+			void *data = kzalloc(size, GFP_KERNEL);
 			if (unlikely(!data))
 				return 0;
 			ret = regset->get(t->task, regset,
-- 
2.25.1