4.16-stable review patch. If anyone has any objections, please let me know.
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From: Kees Cook keescook@chromium.org
commit b5b38200ebe54879a7264cb6f33821f61c586a7e upstream.
Successes in probe_kernel_read() would mask failures in copy_to_user() during read_mem().
Reported-by: Brad Spengler spender@grsecurity.net Fixes: 22ec1a2aea73 ("/dev/mem: Add bounce buffer for copy-out") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/char/mem.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -137,7 +137,7 @@ static ssize_t read_mem(struct file *fil
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 *fil 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);