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

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Message-Id: <20200419100848.63472-1-glider@google.com>
Date:   Sun, 19 Apr 2020 12:08:48 +0200
From:   glider@...gle.com
To:     adobriyan@...il.com, akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, sunhaoyl@...look.com,
        Alexander Potapenko <glider@...gle.com>
Subject: [PATCH] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info()

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>

---

Note: Reported-by: line is subject to change
---
 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 13f25e241ac4..25d489bc9453 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,
-- 
2.26.1.301.g55bc3eb7cb9-goog