Commit 3c91ef69 authored Mar 10, 2020 by Nicholas Johnson Committed by Greg Kroah-Hartman Mar 19, 2020

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
03cd45d2 ("thunderbolt: Prevent crash if non-active NVMem file is
read")

Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20200310132257.23358-10-srinivas.kandagatla@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 061a320b

drivers/nvmem/nvmem-sysfs.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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)

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