Commit 35d13c7a0512 ("platform/x86: thinkpad_acpi: Use strndup_user()
in dispatch_proc_write()") cleaned up dispatch_proc_write() by replacing
the code to copy the passed in data from userspae with strndup_user().
But strndup_user() expects a 0 terminated input buffer and the buffer
passed to dispatch_proc_write() is NOT 0 terminated.
So this change leads to strndup_user() copying some extra random bytes
from userspace till it hits a 0 byte.
This commit reverts the change to use strndup_user() fixing the
buffer being passed to the ibm_struct.write() call back containing extra
junk at the end.
Fixes: 35d13c7a0512 ("platform/x86: thinkpad_acpi: Use strndup_user() in dispatch_proc_write()")
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/platform/x86/thinkpad_acpi.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 92aad746d1f8..8ae2be5871f5 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -886,11 +886,19 @@ static ssize_t dispatch_proc_write(struct file *file,
if (!ibm || !ibm->write)
return -EINVAL;
+ if (count > PAGE_SIZE - 1)
+ return -EINVAL;
+
+ kernbuf = kmalloc(count + 1, GFP_KERNEL);
+ if (!kernbuf)
+ return -ENOMEM;
- kernbuf = strndup_user(userbuf, PAGE_SIZE);
- if (IS_ERR(kernbuf))
- return PTR_ERR(kernbuf);
+ if (copy_from_user(kernbuf, userbuf, count)) {
+ kfree(kernbuf);
+ return -EFAULT;
+ }
+ kernbuf[count] = 0;
ret = ibm->write(kernbuf);
if (ret == 0)
ret = count;
--
2.26.2
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