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bpf, x32: Fix regression caused by commit 24dea04767e6

PATCH Applied Wang YanQing 3 participants 3 messages Jul 25, 2018 – Jul 28, 2018

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Networking Network drivers x86 BPF +1 more subsystems
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Wang YanQing

author maintainer
#0 lore raw

PATCH 1/1 bpf, x32: Fix regression caused by commit 24dea04767e6

Commit 24dea04767e6 ("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 fix it.

Fixes 24dea04767e6 ("bpf, x32: remove ld_abs/ld_ind")
Signed-off-by Wang YanQing <[email protected]>
---
 arch/x86/net/bpf_jit_comp32.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
arch/x86/net/bpf_jit_comp32.c +4 -4
index 5579987..8f6cc71 100644
@@ -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);
Signature · 1 line
1.8.5.6.2.g3d8a54e.dirty
maintainer Applied
#1 lore raw
Quoted 10 lines · Wang YanQing

Commit 24dea04767e6 ("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 fix it.

Fixes 24dea04767e6 ("bpf, x32: remove ld_abs/ld_ind")
Signed-off-by Wang YanQing <[email protected]>

Applied, thanks Wang!

#2 lore raw
In reply to Wang YanQing
Quoted 7 lines

Commit 24dea04767e6 ("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 fix it.

For the record:

Tested it on top of 4.18.0-rc6-00192-g864af0d40cdc on the affected machine and it worked.

Signature · 1 line
Meelis Roos ([email protected])