diff options
| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2025-07-03 13:48:10 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-15 12:13:41 +0200 |
| commit | 6434ca4429ebba5b7909ab5eea7b37acac7bad10 (patch) | |
| tree | 0307afdf9232d29da31bb772847b219a582cef9c | |
| parent | 7989a6056c7e2b022811270d301802fc5834c4ee (diff) | |
bpf: Ensure RCU lock is held around bpf_prog_ksym_find
[ Upstream commit d090326860096df9dac6f27cff76d3f8df44d4f1 ]
Add a warning to ensure RCU lock is held around tree lookup, and then
fix one of the invocations in bpf_stack_walker. The program has an
active stack frame and won't disappear. Use the opportunity to remove
unneeded invocation of is_bpf_text_address.
Fixes: f18b03fabaa9 ("bpf: Implement BPF exceptions")
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | kernel/bpf/core.c | 5 | ||||
| -rw-r--r-- | kernel/bpf/helpers.c | 11 |
2 files changed, 13 insertions, 3 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 68a327158989..767dcb8471f6 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -778,7 +778,10 @@ bool is_bpf_text_address(unsigned long addr) struct bpf_prog *bpf_prog_ksym_find(unsigned long addr) { - struct bpf_ksym *ksym = bpf_ksym_find(addr); + struct bpf_ksym *ksym; + + WARN_ON_ONCE(!rcu_read_lock_held()); + ksym = bpf_ksym_find(addr); return ksym && ksym->prog ? container_of(ksym, struct bpf_prog_aux, ksym)->prog : diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 6cf165c55bda..be4429463599 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2781,9 +2781,16 @@ static bool bpf_stack_walker(void *cookie, u64 ip, u64 sp, u64 bp) struct bpf_throw_ctx *ctx = cookie; struct bpf_prog *prog; - if (!is_bpf_text_address(ip)) - return !ctx->cnt; + /* + * The RCU read lock is held to safely traverse the latch tree, but we + * don't need its protection when accessing the prog, since it has an + * active stack frame on the current stack trace, and won't disappear. + */ + rcu_read_lock(); prog = bpf_prog_ksym_find(ip); + rcu_read_unlock(); + if (!prog) + return !ctx->cnt; ctx->cnt++; if (bpf_is_subprog(prog)) return true; |