> -----Original Message----- > From: Stephen Hemminger <[email protected]> > Sent: Wednesday 24 June 2026 18:55 > To: [email protected] > Cc: Stephen Hemminger <[email protected]>; [email protected]; > Konstantin Ananyev > <[email protected]>; Marat Khalili <[email protected]>; > Ferruh Yigit > <[email protected]> > Subject: [PATCH v5 3/9] bpf: mask shift count in interpreter per RFC 9669 > > The interpreter shifted by the raw immediate or register value, which > is undefined behavior in C when the count is >= the operand width and > trips UBSan. RFC 9669 masks shift counts (0x3f for 64-bit, 0x1f for > 32-bit); mask the count in the LSH/RSH/ARSH cases. > > Fixes: 94972f35a02e ("bpf: add BPF loading and execution framework") > Cc: [email protected] > > Signed-off-by: Stephen Hemminger <[email protected]>
Acked-by: Marat Khalili <[email protected]> > --- > lib/bpf/bpf_exec.c | 31 +++++++++++++++++++++---------- > 1 file changed, 21 insertions(+), 10 deletions(-) > > diff --git a/lib/bpf/bpf_exec.c b/lib/bpf/bpf_exec.c > index d423ef28f5..bb03c9cc2c 100644 > --- a/lib/bpf/bpf_exec.c > +++ b/lib/bpf/bpf_exec.c > @@ -4,6 +4,7 @@ > > #include <stdio.h> > #include <stdint.h> > +#include <limits.h> > > #include <eal_export.h> > #include <rte_common.h> > @@ -43,6 +44,16 @@ > ((reg)[(ins)->dst_reg] = \ > (type)(reg)[(ins)->dst_reg] op (type)(ins)->imm) > > +#define BPF_OP_SHIFT_IMM(reg, ins, op, type) \ > + ((reg)[(ins)->dst_reg] = \ > + (type)(reg)[(ins)->dst_reg] op \ > + ((ins)->imm & (sizeof(type) * CHAR_BIT - 1))) > + > +#define BPF_OP_SHIFT_REG(reg, ins, op, type) \ > + ((reg)[(ins)->dst_reg] = \ > + (type)(reg)[(ins)->dst_reg] op \ > + ((reg)[(ins)->src_reg] & (sizeof(type) * CHAR_BIT - 1))) > + > #define BPF_DIV_ZERO_CHECK(bpf, reg, ins, type) do { \ > if ((type)(reg)[(ins)->src_reg] == 0) { \ > RTE_BPF_LOG_LINE(ERR, \ > @@ -183,10 +194,10 @@ bpf_exec(const struct rte_bpf *bpf, uint64_t > reg[EBPF_REG_NUM]) > BPF_OP_ALU_IMM(reg, ins, |, uint32_t); > break; > case (BPF_ALU | BPF_LSH | BPF_K): > - BPF_OP_ALU_IMM(reg, ins, <<, uint32_t); > + BPF_OP_SHIFT_IMM(reg, ins, <<, uint32_t); > break; > case (BPF_ALU | BPF_RSH | BPF_K): > - BPF_OP_ALU_IMM(reg, ins, >>, uint32_t); > + BPF_OP_SHIFT_IMM(reg, ins, >>, uint32_t); > break; > case (BPF_ALU | BPF_XOR | BPF_K): > BPF_OP_ALU_IMM(reg, ins, ^, uint32_t); > @@ -217,10 +228,10 @@ bpf_exec(const struct rte_bpf *bpf, uint64_t > reg[EBPF_REG_NUM]) > BPF_OP_ALU_REG(reg, ins, |, uint32_t); > break; > case (BPF_ALU | BPF_LSH | BPF_X): > - BPF_OP_ALU_REG(reg, ins, <<, uint32_t); > + BPF_OP_SHIFT_REG(reg, ins, <<, uint32_t); > break; > case (BPF_ALU | BPF_RSH | BPF_X): > - BPF_OP_ALU_REG(reg, ins, >>, uint32_t); > + BPF_OP_SHIFT_REG(reg, ins, >>, uint32_t); > break; > case (BPF_ALU | BPF_XOR | BPF_X): > BPF_OP_ALU_REG(reg, ins, ^, uint32_t); > @@ -262,13 +273,13 @@ bpf_exec(const struct rte_bpf *bpf, uint64_t > reg[EBPF_REG_NUM]) > BPF_OP_ALU_IMM(reg, ins, |, uint64_t); > break; > case (EBPF_ALU64 | BPF_LSH | BPF_K): > - BPF_OP_ALU_IMM(reg, ins, <<, uint64_t); > + BPF_OP_SHIFT_IMM(reg, ins, <<, uint64_t); > break; > case (EBPF_ALU64 | BPF_RSH | BPF_K): > - BPF_OP_ALU_IMM(reg, ins, >>, uint64_t); > + BPF_OP_SHIFT_IMM(reg, ins, >>, uint64_t); > break; > case (EBPF_ALU64 | EBPF_ARSH | BPF_K): > - BPF_OP_ALU_IMM(reg, ins, >>, int64_t); > + BPF_OP_SHIFT_IMM(reg, ins, >>, int64_t); > break; > case (EBPF_ALU64 | BPF_XOR | BPF_K): > BPF_OP_ALU_IMM(reg, ins, ^, uint64_t); > @@ -299,13 +310,13 @@ bpf_exec(const struct rte_bpf *bpf, uint64_t > reg[EBPF_REG_NUM]) > BPF_OP_ALU_REG(reg, ins, |, uint64_t); > break; > case (EBPF_ALU64 | BPF_LSH | BPF_X): > - BPF_OP_ALU_REG(reg, ins, <<, uint64_t); > + BPF_OP_SHIFT_REG(reg, ins, <<, uint64_t); > break; > case (EBPF_ALU64 | BPF_RSH | BPF_X): > - BPF_OP_ALU_REG(reg, ins, >>, uint64_t); > + BPF_OP_SHIFT_REG(reg, ins, >>, uint64_t); > break; > case (EBPF_ALU64 | EBPF_ARSH | BPF_X): > - BPF_OP_ALU_REG(reg, ins, >>, int64_t); > + BPF_OP_SHIFT_REG(reg, ins, >>, int64_t); > break; > case (EBPF_ALU64 | BPF_XOR | BPF_X): > BPF_OP_ALU_REG(reg, ins, ^, uint64_t); > -- > 2.53.0
