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| author |   Dave Marchevsky <davemarchevsky@fb.com> | 2023-04-21 00:44:31 -0700 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2023-04-21 16:31:37 +0200 |
| commit | 4ab07209d5cc8cb6d2a5324c07b3efc3b2fde494 (patch) | |
| tree | f1dcb589695870ac2db152716ae539f73e10e475 | |
| parent | bpf: Fix race between btf_put and btf_idr walk. (diff) | |
| download | wireguard-linux-4ab07209d5cc8cb6d2a5324c07b3efc3b2fde494.tar.xz wireguard-linux-4ab07209d5cc8cb6d2a5324c07b3efc3b2fde494.zip | |
bpf: Fix bpf_refcount_acquire's refcount_t address calculation
When calculating the address of the refcount_t struct within a local
kptr, bpf_refcount_acquire_impl should add refcount_off bytes to the
address of the local kptr. Due to some missing parens, the function is
incorrectly adding sizeof(refcount_t) * refcount_off bytes. This patch
fixes the calculation.
Due to the incorrect calculation, bpf_refcount_acquire_impl was trying
to refcount_inc some memory well past the end of local kptrs, resulting
in kasan and refcount complaints, as reported in [0]. In that thread,
Florian and Eduard discovered that bpf selftests written in the new
style - with __success and an expected __retval, specifically - were
not actually being run. As a result, selftests added in bpf_refcount
series weren't really exercising this behavior, and thus didn't unearth
the bug.
With this fixed behavior it's safe to revert commit 7c4b96c00043
("selftests/bpf: disable program test run for progs/refcounted_kptr.c"),
this patch does so.
[0] https://lore.kernel.org/bpf/ZEEp+j22imoN6rn9@strlen.de/
Fixes: 7c50b1cb76ac ("bpf: Add bpf_refcount_acquire kfunc")
Reported-by: Florian Westphal <fw@strlen.de>
Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20230421074431.3548349-1-davemarchevsky@fb.com
| -rw-r--r-- | kernel/bpf/helpers.c | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/refcounted_kptr.c | 8 |
2 files changed, 5 insertions, 5 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 00e5fb0682ac..8d368fa353f9 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1925,7 +1925,7 @@ __bpf_kfunc void *bpf_refcount_acquire_impl(void *p__refcounted_kptr, void *meta /* Could just cast directly to refcount_t *, but need some code using * bpf_refcount type so that it is emitted in vmlinux BTF */ - ref = (struct bpf_refcount *)p__refcounted_kptr + meta->record->refcount_off; + ref = (struct bpf_refcount *)(p__refcounted_kptr + meta->record->refcount_off); refcount_inc((refcount_t *)ref); return (void *)p__refcounted_kptr; diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr.c b/tools/testing/selftests/bpf/progs/refcounted_kptr.c index b6b2d4f97b19..1d348a225140 100644 --- a/tools/testing/selftests/bpf/progs/refcounted_kptr.c +++ b/tools/testing/selftests/bpf/progs/refcounted_kptr.c @@ -219,7 +219,7 @@ static long __read_from_unstash(int idx) #define INSERT_READ_BOTH(rem_tree, rem_list, desc) \ SEC("tc") \ __description(desc) \ -__success /* __retval(579) temporarily disabled */ \ +__success __retval(579) \ long insert_and_remove_tree_##rem_tree##_list_##rem_list(void *ctx) \ { \ long err, tree_data, list_data; \ @@ -258,7 +258,7 @@ INSERT_READ_BOTH(false, true, "insert_read_both: remove from list"); #define INSERT_READ_BOTH(rem_tree, rem_list, desc) \ SEC("tc") \ __description(desc) \ -__success /* __retval(579) temporarily disabled */ \ +__success __retval(579) \ long insert_and_remove_lf_tree_##rem_tree##_list_##rem_list(void *ctx) \ { \ long err, tree_data, list_data; \ @@ -296,7 +296,7 @@ INSERT_READ_BOTH(false, true, "insert_read_both_list_first: remove from list"); #define INSERT_DOUBLE_READ_AND_DEL(read_fn, read_root, desc) \ SEC("tc") \ __description(desc) \ -__success /* temporarily __retval(-1) disabled */ \ +__success __retval(-1) \ long insert_double_##read_fn##_and_del_##read_root(void *ctx) \ { \ long err, list_data; \ @@ -329,7 +329,7 @@ INSERT_DOUBLE_READ_AND_DEL(__read_from_list, head, "insert_double_del: 2x read-a #define INSERT_STASH_READ(rem_tree, desc) \ SEC("tc") \ __description(desc) \ -__success /* __retval(84) temporarily disabled */ \ +__success __retval(84) \ long insert_rbtree_and_stash__del_tree_##rem_tree(void *ctx) \ { \ long err, tree_data, map_data; \ |