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ACPI: custom_method: fix a possible memory leak

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commit 1cfd8956437f842836e8a066b40d1ec2fc01f13e upstream.

In cm_write(), if the 'buf' is allocated memory but not fully consumed,
it is possible to reallocate the buffer without freeing it by passing
'*ppos' as 0 on a subsequent call.

Add an explicit kfree() before kzalloc() to prevent the possible memory
leak.

Fixes: 526b4af47f ("ACPI: Split out custom_method functionality into an own driver")
Signed-off-by: Mark Langsdorf <mlangsdo@redhat.com>
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mark Langsdorf 2021-04-27 13:54:33 -05:00 committed by Greg Kroah-Hartman
parent 62dc2440eb
commit d11fdbee28
1 changed files with 2 additions and 0 deletions
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drivers/acpi/custom_method.c
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@ -42,6 +42,8 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
sizeof(struct acpi_table_header)))
return -EFAULT;
uncopied_bytes = max_size = table.length;
/* make sure the buf is not allocated */
kfree(buf);
buf = kzalloc(max_size, GFP_KERNEL);
if (!buf)
return -ENOMEM;