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Commit b5b38200 authored by Kees Cook's avatar Kees Cook Committed by Greg Kroah-Hartman
Browse files

/dev/mem: Avoid overwriting "err" in read_mem() 



Successes in probe_kernel_read() would mask failures in copy_to_user()
during read_mem().

Reported-by: default avatarBrad Spengler <spender@grsecurity.net>
Fixes: 22ec1a2a ("/dev/mem: Add bounce buffer for copy-out")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b24d0d5b

drivers/char/mem.c

+3 −3
Original line number Diff line number Diff line
@@ -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);