Revert "bpf: correct slot_type marking logic to allow more stack slot…

… sharing" ANBZ: torvalds#342 This reverts commit 8f4a724. Signed-off-by: Qiao Ma <mqaio@linux.alibaba.com> Acked-by: Mao Wenan <wenan.mao@linux.alibaba.com> Acked-by: Tony Lu <tonylu@linux.alibaba.com>
gatieme · Apr 20, 2022 · 825ad97 · 825ad97
1 parent fed7997
commit 825ad97
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Showing 2 changed files with 2 additions and 37 deletions.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
@@ -1040,10 +1040,6 @@ static int check_stack_write(struct bpf_verifier_env *env,
 
 		/* regular write of data into stack destroys any spilled ptr */
 		state->stack[spi].spilled_ptr.type = NOT_INIT;
-		/* Mark slots as STACK_MISC if they belonged to spilled ptr. */
-		if (state->stack[spi].slot_type[0] == STACK_SPILL)
-			for (i = 0; i < BPF_REG_SIZE; i++)
-				state->stack[spi].slot_type[i] = STACK_MISC;
 
 		/* only mark the slot as written if all 8 bytes were written
 		 * otherwise read propagation may incorrectly stop too soon
@@ -1061,7 +1057,6 @@ static int check_stack_write(struct bpf_verifier_env *env,
 		    register_is_null(&cur->regs[value_regno]))
 			type = STACK_ZERO;
 
-		/* Mark slots affected by this stack write. */
 		for (i = 0; i < size; i++)
 			state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] =
 				type;

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
@@ -956,44 +956,14 @@ static struct bpf_test tests[] = {
 			BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
 			/* mess up with R1 pointer on stack */
 			BPF_ST_MEM(BPF_B, BPF_REG_10, -7, 0x23),
-			/* fill back into R0 is fine for priv.
-			 * R0 now becomes SCALAR_VALUE.
-			 */
+			/* fill back into R0 should fail */
 			BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
-			/* Load from R0 should fail. */
-			BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 8),
 			BPF_EXIT_INSN(),
 		},
 		.errstr_unpriv = "attempt to corrupt spilled",
-		.errstr = "R0 invalid mem access 'inv",
+		.errstr = "corrupted spill",
 		.result = REJECT,
 	},
-	{
-		"check corrupted spill/fill, LSB",
-		.insns = {
-			BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
-			BPF_ST_MEM(BPF_H, BPF_REG_10, -8, 0xcafe),
-			BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
-			BPF_EXIT_INSN(),
-		},
-		.errstr_unpriv = "attempt to corrupt spilled",
-		.result_unpriv = REJECT,
-		.result = ACCEPT,
-		.retval = POINTER_VALUE,
-	},
-	{
-		"check corrupted spill/fill, MSB",
-		.insns = {
-			BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
-			BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 0x12345678),
-			BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
-			BPF_EXIT_INSN(),
-		},
-		.errstr_unpriv = "attempt to corrupt spilled",
-		.result_unpriv = REJECT,
-		.result = ACCEPT,
-		.retval = POINTER_VALUE,
-	},
 	{
 		"invalid src register in STX",
 		.insns = {