In the Linux kernel, the following vulnerability has been resolved: smb: client: validate absolute…

Why it is Yellow

• CVSS 7.8 high
• On your watchlist: linux kernel

References

• https://git.kernel.org/stable/c/23c240d9509e15f72e4112fc95f0160ab32ec430
• https://git.kernel.org/stable/c/6913ff607c2bc8694193e1fcc40bf16d75f35f16

Original description

In the Linux kernel, the following vulnerability has been resolved: smb: client: validate absolute native symlink targets before NT fixups With symlinkroot unset, an absolute target is copied without conversion to an NT drive path. Later code still assumes an NT prefix is present when modifying the target and calculating the print name length. For "/ab", this causes two failures: sym[5] and path[5] are written past their allocations, and plen -= 2 * poff subtracts an assumed 8-byte prefix from a 6-byte UTF-16 target, wrapping u16 plen to 65534. That underflow causes another overflow: memcpy() copies 65534 bytes into a 24-byte buffer. A user with write access to a mounted share can trigger these bugs with default settings. Validate the NT drive prefix, including an ASCII drive letter, before accessing fixed offsets or subtracting the prefix length.