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bpf, x32: Fix regression caused by commit 24dea04767 

Commit 24dea04767 ("bpf, x32: remove ld_abs/ld_ind")
removed the 4 /* Extra space for skb_copy_bits buffer */
from _STACK_SIZE, but it didn't fix the concerned code
in emit_prologue and emit_epilogue, and this error will
bring very strange kernel runtime errors. This patch
fixes it.

Fixes: 24dea04767 ("bpf, x32: remove ld_abs/ld_ind")
Reported-by: Meelis Roos <mroos@linux.ee>
Bisected-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Wang YanQing 2018-07-26 00:46:11 +08:00 committed by Daniel Borkmann
parent 684cce1c31
commit 9e4e5b5c86
1 changed files with 4 additions and 4 deletions
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8
arch/x86/net/bpf_jit_comp32.c
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@ -1441,8 +1441,8 @@ static void emit_prologue(u8 **pprog, u32 stack_depth)
/* sub esp,STACK_SIZE */
EMIT2_off32(0x81, 0xEC, STACK_SIZE);
/* sub ebp,SCRATCH_SIZE+4+12*/
EMIT3(0x83, add_1reg(0xE8, IA32_EBP), SCRATCH_SIZE + 16);
/* sub ebp,SCRATCH_SIZE+12*/
EMIT3(0x83, add_1reg(0xE8, IA32_EBP), SCRATCH_SIZE + 12);
/* xor ebx,ebx */
EMIT2(0x31, add_2reg(0xC0, IA32_EBX, IA32_EBX));
@ -1475,8 +1475,8 @@ static void emit_epilogue(u8 **pprog, u32 stack_depth)
/* mov edx,dword ptr [ebp+off]*/
EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX), STACK_VAR(r0[1]));
/* add ebp,SCRATCH_SIZE+4+12*/
EMIT3(0x83, add_1reg(0xC0, IA32_EBP), SCRATCH_SIZE + 16);
/* add ebp,SCRATCH_SIZE+12*/
EMIT3(0x83, add_1reg(0xC0, IA32_EBP), SCRATCH_SIZE + 12);
/* mov ebx,dword ptr [ebp-12]*/
EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EBX), -12);