rar4 reader: protect copy_..._to_unp from too-big or too-small length (CVE-2024-20696) #2172
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copy_from_lzss_window_to_unp unnecessarily took an `int` parameter where both of its callers were holding a `size_t`. A lzss opcode chain could be cosntructed that resulted in a negative copy length, which when passed into memcpy would result in a very, very large positive number. Switching copy_from_lzss_window_to_unp to take a `size_t` allows it to properly bounds-check length. In addition, this patch also ensures that `length` is not itself larger than the destination buffer.
DHowett
changed the title
|
There's a test file for this, but I have as yet been unable to minimize it. It's currently attached to GHSA-266m-xmh8-88vf, and it is 117kb. I can check it in directly without trying to minimize it if that would be preferred! |
DHowett
commented
May 7, 2024
mmatuska
approved these changes
May 9, 2024
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copy_from_lzss_window_to_unp unnecessarily took an
intparameter where both of its callers were holding asize_t.A lzss opcode chain could be constructed that resulted in a negative copy length, which when passed into memcpy would result in a very, very large positive number.
Switching copy_from_lzss_window_to_unp to take a
size_tallows it to properly bounds-check length.In addition, this patch also ensures that
lengthis not itself larger than the destination buffer.