From 836b2fe544a5e9b5ce116622cb36fba33838c6fd Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 4 Sep 2026 01:33:23 -0700 Subject: selftests/bpf: Check that JMP32 pointer vs zero jumps are not predicted Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which the verifier used to skip, contains an out of bounds map value access, hence w/o the previous patch the program is accepted. See previous patch for detailed description. Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- samples/bpf/hash_func01.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 samples/bpf/hash_func01.h (limited to 'samples/bpf/hash_func01.h') diff --git a/samples/bpf/hash_func01.h b/samples/bpf/hash_func01.h new file mode 100644 index 000000000..38255812e --- /dev/null +++ b/samples/bpf/hash_func01.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: LGPL-2.1 + * + * Based on Paul Hsieh's (LGPG 2.1) hash function + * From: http://www.azillionmonkeys.com/qed/hash.html + */ + +#define get16bits(d) (*((const __u16 *) (d))) + +static __always_inline +__u32 SuperFastHash (const char *data, int len, __u32 initval) { + __u32 hash = initval; + __u32 tmp; + int rem; + + if (len <= 0 || data == NULL) return 0; + + rem = len & 3; + len >>= 2; + + /* Main loop */ +#pragma clang loop unroll(full) + for (;len > 0; len--) { + hash += get16bits (data); + tmp = (get16bits (data+2) << 11) ^ hash; + hash = (hash << 16) ^ tmp; + data += 2*sizeof (__u16); + hash += hash >> 11; + } + + /* Handle end cases */ + switch (rem) { + case 3: hash += get16bits (data); + hash ^= hash << 16; + hash ^= ((signed char)data[sizeof (__u16)]) << 18; + hash += hash >> 11; + break; + case 2: hash += get16bits (data); + hash ^= hash << 11; + hash += hash >> 17; + break; + case 1: hash += (signed char)*data; + hash ^= hash << 10; + hash += hash >> 1; + } + + /* Force "avalanching" of final 127 bits */ + hash ^= hash << 3; + hash += hash >> 5; + hash ^= hash << 4; + hash += hash >> 17; + hash ^= hash << 25; + hash += hash >> 6; + + return hash; +} -- cgit v1.3.1