From: Jann Horn <jannh@google.com> stable inclusion from stable-v6.6.67 commit 68d23ee1bdf1c7ce499897d738033d67db46fffa category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBJ838 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 7d0d673627e20cfa3b21a829a896ce03b58a4f1c upstream. Currently, the pointer stored in call->prog_array is loaded in __uprobe_perf_func(), with no RCU annotation and no immediately visible RCU protection, so it looks as if the loaded pointer can immediately be dangling. Later, bpf_prog_run_array_uprobe() starts a RCU-trace read-side critical section, but this is too late. It then uses rcu_dereference_check(), but this use of rcu_dereference_check() does not actually dereference anything. Fix it by aligning the semantics to bpf_prog_run_array(): Let the caller provide rcu_read_lock_trace() protection and then load call->prog_array with rcu_dereference_check(). This issue seems to be theoretical: I don't know of any way to reach this code without having handle_swbp() further up the stack, which is already holding a rcu_read_lock_trace() lock, so where we take rcu_read_lock_trace() in __uprobe_perf_func()/bpf_prog_run_array_uprobe() doesn't actually have any effect. Fixes: 8c7dcb84e3b7 ("bpf: implement sleepable uprobes by chaining gps") Suggested-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20241210-bpf-fix-uprobe-uaf-v4-1-5fc8959b2b74@go... Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- include/linux/bpf.h | 13 +++++-------- kernel/trace/trace_uprobe.c | 6 +++++- 2 files changed, 10 insertions(+), 9 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 73ef8dda7ada..8f4c303080a8 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2078,26 +2078,25 @@ bpf_prog_run_array(const struct bpf_prog_array *array, * rcu-protected dynamically sized maps. */ static __always_inline u32 -bpf_prog_run_array_uprobe(const struct bpf_prog_array __rcu *array_rcu, +bpf_prog_run_array_uprobe(const struct bpf_prog_array *array, const void *ctx, bpf_prog_run_fn run_prog) { const struct bpf_prog_array_item *item; const struct bpf_prog *prog; - const struct bpf_prog_array *array; struct bpf_run_ctx *old_run_ctx; struct bpf_trace_run_ctx run_ctx; u32 ret = 1; might_fault(); + RCU_LOCKDEP_WARN(!rcu_read_lock_trace_held(), "no rcu lock held"); + + if (unlikely(!array)) + return ret; - rcu_read_lock_trace(); migrate_disable(); run_ctx.is_uprobe = true; - array = rcu_dereference_check(array_rcu, rcu_read_lock_trace_held()); - if (unlikely(!array)) - goto out; old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx); item = &array->items[0]; while ((prog = READ_ONCE(item->prog))) { @@ -2112,9 +2111,7 @@ bpf_prog_run_array_uprobe(const struct bpf_prog_array __rcu *array_rcu, rcu_read_unlock(); } bpf_reset_run_ctx(old_run_ctx); -out: migrate_enable(); - rcu_read_unlock_trace(); return ret; } diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 791c0723212b..9110a759e882 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -1346,9 +1346,13 @@ static void __uprobe_perf_func(struct trace_uprobe *tu, #ifdef CONFIG_BPF_EVENTS if (bpf_prog_array_valid(call)) { + const struct bpf_prog_array *array; u32 ret; - ret = bpf_prog_run_array_uprobe(call->prog_array, regs, bpf_prog_run); + rcu_read_lock_trace(); + array = rcu_dereference_check(call->prog_array, rcu_read_lock_trace_held()); + ret = bpf_prog_run_array_uprobe(array, regs, bpf_prog_run); + rcu_read_unlock_trace(); if (!ret) return; } -- 2.34.1