leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

arm64: bpf: fix buffer pointer

Browse Source 
During code review, I noticed we were passing a bad buffer pointer
to bpf_load_pointer helper function called by jitted code.

Point to the buffer allocated by JIT, so we don't silently corrupt
other parts of the stack.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Zi Shen Lim 2015-11-18 00:56:02 -08:00 committed by David S. Miller
parent 508dc0648c
commit f4b16fce7a
1 changed files with 13 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
arch/arm64/net/bpf_jit_comp.c
View File

@ -139,6 +139,12 @@ static inline int epilogue_offset(const struct jit_ctx *ctx)
/* Stack must be multiples of 16B */
#define STACK_ALIGN(sz) (((sz) + 15) & ~15)
#define _STACK_SIZE \
(MAX_BPF_STACK \
+ 4 /* extra for skb_copy_bits buffer */)
#define STACK_SIZE STACK_ALIGN(_STACK_SIZE)
static void build_prologue(struct jit_ctx *ctx)
{
const u8 r6 = bpf2a64[BPF_REG_6];
@ -150,10 +156,6 @@ static void build_prologue(struct jit_ctx *ctx)
const u8 rx = bpf2a64[BPF_REG_X];
const u8 tmp1 = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
int stack_size = MAX_BPF_STACK;
stack_size += 4; /* extra for skb_copy_bits buffer */
stack_size = STACK_ALIGN(stack_size);
/*
* BPF prog stack layout
@ -165,12 +167,13 @@ static void build_prologue(struct jit_ctx *ctx)
* | ... | callee saved registers
* +-----+
* | | x25/x26
* BPF fp register => -80:+-----+
* BPF fp register => -80:+-----+ <= (BPF_FP)
* | |
* | ... | BPF prog stack
* | |
* | |
* current A64_SP => +-----+
* +-----+ <= (BPF_FP - MAX_BPF_STACK)
* |RSVD | JIT scratchpad
* current A64_SP => +-----+ <= (BPF_FP - STACK_SIZE)
* | |
* | ... | Function call stack
* | |
@ -196,7 +199,7 @@ static void build_prologue(struct jit_ctx *ctx)
emit(A64_MOV(1, fp, A64_SP), ctx);
/* Set up function call stack */
emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
emit(A64_SUB_I(1, A64_SP, A64_SP, STACK_SIZE), ctx);
/* Clear registers A and X */
emit_a64_mov_i64(ra, 0, ctx);
@ -213,13 +216,9 @@ static void build_epilogue(struct jit_ctx *ctx)
const u8 fp = bpf2a64[BPF_REG_FP];
const u8 tmp1 = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
int stack_size = MAX_BPF_STACK;
stack_size += 4; /* extra for skb_copy_bits buffer */
stack_size = STACK_ALIGN(stack_size);
/* We're done with BPF stack */
emit(A64_ADD_I(1, A64_SP, A64_SP, stack_size), ctx);
emit(A64_ADD_I(1, A64_SP, A64_SP, STACK_SIZE), ctx);
/* Restore fs (x25) and x26 */
emit(A64_POP(fp, A64_R(26), A64_SP), ctx);
@ -658,7 +657,7 @@ emit_cond_jmp:
return -EINVAL;
}
emit_a64_mov_i64(r3, size, ctx);
emit(A64_ADD_I(1, r4, fp, MAX_BPF_STACK), ctx);
emit(A64_SUB_I(1, r4, fp, STACK_SIZE), ctx);
emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx);
emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
emit(A64_MOV(1, A64_FP, A64_SP), ctx);