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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
03cd45d2e2 ("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>
This commit is contained in:
Nicholas Johnson 2020-03-10 13:22:52 +00:00 committed by Greg Kroah-Hartman
parent 061a320b32
commit 3c91ef69a3
1 changed files with 6 additions and 0 deletions
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6
drivers/nvmem/nvmem-sysfs.c
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@ -56,6 +56,9 @@ static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
count = round_down(count, nvmem->word_size); count = round_down(count, nvmem->word_size);
if (!nvmem->reg_read)
return -EPERM;
rc = nvmem->reg_read(nvmem->priv, pos, buf, count); rc = nvmem->reg_read(nvmem->priv, pos, buf, count);
if (rc) 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); count = round_down(count, nvmem->word_size);
if (!nvmem->reg_write)
return -EPERM;
rc = nvmem->reg_write(nvmem->priv, pos, buf, count); rc = nvmem->reg_write(nvmem->priv, pos, buf, count);
if (rc) if (rc)