Description: bpf: Fix truncation handling for mod32 dst reg wrt zero References: https://www.openwall.com/lists/oss-security/2021/03/23/2 Notes: carnil> Introduced by 468f6eafa6c4 ("bpf: fix 32-bit ALU op carnil> verification") (4.15-rc5) but f6b1b3bf0d5f ("bpf: fix subprog carnil> verifier bypass by div/mod by 0 exception") (4.16-rc1) is carnil> necessary to exploit the issue. carnil> Will require as well e88b2c6e5a4d ("bpf: Fix 32 bit src carnil> register truncation on div/mod") as prerequisite. carnil> This last pre-requisite commit though would depend on carnil> 092ed0968bb6 ("bpf: verifier support JMP32") which does not carnil> seem to make it possible to backport the fixes in 4.19.y carnil> easily. Bugs: upstream: released (5.12-rc1) [9b00f1b78809309163dda2d044d9e94a3c0248a3] 5.10-upstream-stable: released (5.10.19) [3320bae8c115863b6f17993c2b7970f7f419da57] 4.19-upstream-stable: released (4.19.206) [39f74b7c81cca139c05757d9c8f9d1e35fbbf56b] 4.9-upstream-stable: N/A "Vulnerable code introduced later" sid: released (5.10.19-1) 5.10-bullseye-security: N/A "Fixed before branching point" 4.19-buster-security: released (4.19.208-1) 4.9-stretch-security: N/A "Vulnerable code introduced later"