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Commit 9e4e5b5c authored by Wang YanQing's avatar Wang YanQing Committed by Daniel Borkmann
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bpf, x32: Fix regression caused by commit 24dea047 



Commit 24dea047 ("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: 24dea047 ("bpf, x32: remove ld_abs/ld_ind")
Reported-by: default avatarMeelis Roos <mroos@linux.ee>
Bisected-by: default avatarMeelis Roos <mroos@linux.ee>
Signed-off-by: default avatarWang YanQing <udknight@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 684cce1c

arch/x86/net/bpf_jit_comp32.c

+4 −4
Original line number Diff line number Diff line
@@ -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);