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Subject[PATCH v2 2/3] nvmem: check for NULL reg_read and reg_write before dereferencing
Date
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 <nicholas.johnson-opensource@outlook.com.au>
---
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 00d3259ea..9312e1d6f 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)
--
2.25.1
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