From 3c91ef69a3e94f78546b246225ed573fbf1735b4 Mon Sep 17 00:00:00 2001 From: Nicholas Johnson Date: Tue, 10 Mar 2020 13:22:52 +0000 Subject: [PATCH] nvmem: check for NULL reg_read and reg_write before dereferencing Return -EPERM if reg_read is NULL in bin_attr_nvmem_read() or if reg_write is NULL in bin_attr_nvmem_write(). This prevents NULL dereferences such as the one described in 03cd45d2e219 ("thunderbolt: Prevent crash if non-active NVMem file is read") Signed-off-by: Nicholas Johnson Cc: stable Signed-off-by: Srinivas Kandagatla Link: https://lore.kernel.org/r/20200310132257.23358-10-srinivas.kandagatla@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/nvmem/nvmem-sysfs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/nvmem/nvmem-sysfs.c b/drivers/nvmem/nvmem-sysfs.c index 9e0c429cd08a..8759c4470012 100644 --- a/drivers/nvmem/nvmem-sysfs.c +++ b/drivers/nvmem/nvmem-sysfs.c @@ -56,6 +56,9 @@ static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj, count = round_down(count, nvmem->word_size); + if (!nvmem->reg_read) + return -EPERM; + rc = nvmem->reg_read(nvmem->priv, pos, buf, count); if (rc) @@ -90,6 +93,9 @@ static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj, count = round_down(count, nvmem->word_size); + if (!nvmem->reg_write) + return -EPERM; + rc = nvmem->reg_write(nvmem->priv, pos, buf, count); if (rc)