| Description: | In the Linux kernel, the following vulnerability has been resolved:
media: stk1160: fix bounds checking in stk1160_copy_video() The
subtract in this condition is reversed. The ->length is the length of
the buffer. The ->bytesused is how many bytes we have copied thus far.
When the condition is reversed that means the result of the
subtraction is always negative but since it's unsigned then the result
is a very high positive value. That means the overflow check is never
true. Additionally, the ->bytesused doesn't actually work for this
purpose because we're not writing to "buf->mem + buf->bytesused".
Instead, the math to calculate the destination where we are writing is
a bit involved. You calculate the number of full lines already
written, multiply by two, skip a line if necessary so that we start on
an odd numbered line, and add the offset into the line. To fix this
buffer overflow, just take the actual destination where we are
writing, if the offset is already out of bounds print an error and
return. Otherwise, write up to buf->length bytes.
|
