Messages in this thread Patch in this message | | | Date | Tue, 27 Mar 2018 14:06:14 -0700 | From | Kees Cook <> | Subject | [PATCH] /dev/mem: Avoid overwriting "err" in read_mem() |
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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> --- 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 052011bcf100..ffeb60d3434c 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); -- 2.7.4
-- Kees Cook Pixel Security
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