diff mbox series

[v6,bpf-next,04/17] bpf: derive smin32/smax32 from umin32/umax32 bounds

Message ID 20231102033759.2541186-5-andrii@kernel.org (mailing list archive)
State Accepted
Commit f188765f23a58bebce48bd078effa95733fe37de
Delegated to: BPF
Headers show
Series BPF register bounds logic and testing improvements | expand

Checks

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bpf/vmtest-bpf-next-PR success PR summary
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netdev/series_format fail Series longer than 15 patches (and no cover letter)
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1356 this patch: 1356
netdev/cc_maintainers warning 8 maintainers not CCed: jolsa@kernel.org sdf@google.com john.fastabend@gmail.com kpsingh@kernel.org song@kernel.org yonghong.song@linux.dev haoluo@google.com martin.lau@linux.dev
netdev/build_clang success Errors and warnings before: 1370 this patch: 1370
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netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1381 this patch: 1381
netdev/checkpatch warning WARNING: line length of 88 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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bpf/vmtest-bpf-next-VM_Test-6 success Logs for aarch64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on aarch64 with gcc
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bpf/vmtest-bpf-next-VM_Test-22 success Logs for x86_64-gcc / test (test_verifier, false, 360) / test_verifier on x86_64 with gcc
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bpf/vmtest-bpf-next-VM_Test-24 success Logs for x86_64-llvm-16 / build / build for x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-25 success Logs for x86_64-llvm-16 / test (test_maps, false, 360) / test_maps on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-28 success Logs for x86_64-llvm-16 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-29 success Logs for x86_64-llvm-16 / veristat
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bpf/vmtest-bpf-next-VM_Test-27 success Logs for x86_64-llvm-16 / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-13 success Logs for s390x-gcc / test (test_verifier, false, 360) / test_verifier on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-11 success Logs for s390x-gcc / test (test_progs, false, 360) / test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-12 success Logs for s390x-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-10 success Logs for s390x-gcc / test (test_maps, false, 360) / test_maps on s390x with gcc

Commit Message

Andrii Nakryiko Nov. 2, 2023, 3:37 a.m. UTC 
All the logic that applies to u64 vs s64, equally applies for u32 vs s32
relationships (just taken in a smaller 32-bit numeric space). So do the
same deduction of smin32/smax32 from umin32/umax32, if we can.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 kernel/bpf/verifier.c | 7 +++++++
 1 file changed, 7 insertions(+)
diff mbox series

Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8a4cdd2787ec..b93818abe7fc 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2324,6 +2324,13 @@  static void __update_reg_bounds(struct bpf_reg_state *reg)
 /* Uses signed min/max values to inform unsigned, and vice-versa */
 static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
 {
+	/* if u32 range forms a valid s32 range (due to matching sign bit),
+	 * try to learn from that
+	 */
+	if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) {
+		reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value);
+		reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value);
+	}
 	/* Learn sign from signed bounds.
 	 * If we cannot cross the sign boundary, then signed and unsigned bounds
 	 * are the same, so combine.  This works even in the negative case, e.g.