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bpf/verifier: Add spi variable to check_stack_write()

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Extracted from commit dc503a8ad9 "bpf/verifier: track liveness for
pruning".

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ben Hutchings 2018-12-05 22:45:15 +00:00 committed by Greg Kroah-Hartman
parent 3c4bb079e1
commit 168cb9b7b2
1 changed files with 3 additions and 5 deletions
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8
kernel/bpf/verifier.c
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@ -572,7 +572,7 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
static int check_stack_write(struct verifier_state *state, int off, int size,
int value_regno)
{
int i;
int i, spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE;
/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
* so it's aligned access and [off, off + size) are within stack limits
*/
@ -587,15 +587,13 @@ static int check_stack_write(struct verifier_state *state, int off, int size,
}
/* save register state */
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
state->regs[value_regno];
state->spilled_regs[spi] = state->regs[value_regno];
for (i = 0; i < BPF_REG_SIZE; i++)
state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
} else {
/* regular write of data into stack */
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
(struct reg_state) {};
state->spilled_regs[spi] = (struct reg_state) {};
for (i = 0; i < size; i++)
state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;