From 5f834dd24baec1f9926e8a06609e0906fd607b06 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 27 Mar 2018 14:06:14 -0700 Subject: [PATCH] /dev/mem: Avoid overwriting "err" in read_mem() commit b5b38200ebe54879a7264cb6f33821f61c586a7e upstream. Successes in probe_kernel_read() would mask failures in copy_to_user() during read_mem(). Reported-by: Brad Spengler Fixes: 22ec1a2aea73 ("/dev/mem: Add bounce buffer for copy-out") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman --- drivers/char/mem.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 3a70dba2c645..f11224a5dc5c 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -137,7 +137,7 @@ static ssize_t read_mem(struct file *file, char __user *buf, while (count > 0) { unsigned long remaining; - int allowed; + int allowed, probe; sz = size_inside_page(p, count); @@ -160,9 +160,9 @@ static ssize_t read_mem(struct file *file, char __user *buf, if (!ptr) goto failed; - err = probe_kernel_read(bounce, ptr, sz); + probe = probe_kernel_read(bounce, ptr, sz); unxlate_dev_mem_ptr(p, ptr); - if (err) + if (probe) goto failed; remaining = copy_to_user(buf, bounce, sz); -- 2.20.1