From: Frank van der Linden <fllinden@amazon.com>
To: <stable@vger.kernel.org>
Cc: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
<yhs@fb.com>, <john.fastabend@gmail.com>, <samjonas@amazon.com>
Subject: [PATCH 4.14 01/15] bpf: Fix backport of "bpf: restrict unknown scalars of mixed signed bounds for unprivileged"
Date: Sat, 1 May 2021 04:30:00 +0000 [thread overview]
Message-ID: <20210501043014.33300-2-fllinden@amazon.com> (raw)
In-Reply-To: <20210501043014.33300-1-fllinden@amazon.com>
From: Samuel Mendoza-Jonas <samjonas@amazon.com>
The 4.14 backport of 9d7eceede ("bpf: restrict unknown scalars of mixed
signed bounds for unprivileged") adds the PTR_TO_MAP_VALUE check to the
wrong location in adjust_ptr_min_max_vals(), most likely because 4.14
doesn't include the commit that updates the if-statement to a
switch-statement (aad2eeaf4 "bpf: Simplify ptr_min_max_vals adjustment").
Move the check to the proper location in adjust_ptr_min_max_vals().
Fixes: 17efa65350c5a ("bpf: restrict unknown scalars of mixed signed bounds for unprivileged")
Signed-off-by: Samuel Mendoza-Jonas <samjonas@amazon.com>
Reviewed-by: Frank van der Linden <fllinden@amazon.com>
Reviewed-by: Ethan Chen <yishache@amazon.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/verifier.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0c3a9302be93..9e9b7c076bcb 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2204,6 +2204,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
dst);
return -EACCES;
}
+ if (ptr_reg->type == PTR_TO_MAP_VALUE) {
+ if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) {
+ verbose("R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n",
+ off_reg == dst_reg ? dst : src);
+ return -EACCES;
+ }
+ }
/* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
* The id may be overwritten later if we create a new variable offset.
@@ -2349,13 +2356,6 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
verbose("R%d bitwise operator %s on pointer prohibited\n",
dst, bpf_alu_string[opcode >> 4]);
return -EACCES;
- case PTR_TO_MAP_VALUE:
- if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) {
- verbose("R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n",
- off_reg == dst_reg ? dst : src);
- return -EACCES;
- }
- /* fall-through */
default:
/* other operators (e.g. MUL,LSH) produce non-pointer results */
if (!env->allow_ptr_leaks)
--
2.23.3
next prev parent reply other threads:[~2021-05-01 4:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 4:29 [PATCH 4.14 00/15] fix backports, add CVE-2021-29155 fixes Frank van der Linden
2021-05-01 4:30 ` Frank van der Linden [this message]
2021-05-01 4:30 ` [PATCH 4.14 02/15] bpf: fix up selftests after backports were fixed Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 03/15] bpf, selftests: Fix up some test_verifier cases for unprivileged Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 04/15] bpf: Move off_reg into sanitize_ptr_alu Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 05/15] bpf: Ensure off_reg has no mixed signed bounds for all types Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 06/15] bpf: Rework ptr_limit into alu_limit and add common error path Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 07/15] bpf: Improve verifier error messages for users Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 08/15] bpf: Refactor and streamline bounds check into helper Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 09/15] bpf: Move sanitize_val_alu out of op switch Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 10/15] bpf: Tighten speculative pointer arithmetic mask Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 11/15] bpf: Update selftests to reflect new error states Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 12/15] bpf: do not allow root to mangle valid pointers Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 13/15] bpf/verifier: disallow pointer subtraction Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 14/15] selftests/bpf: fix test_align Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 15/15] selftests/bpf: make 'dubious pointer arithmetic' test useful Frank van der Linden
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