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l=1867; h=from:subject; bh=gumr+xxSUYFcCvf/7ZCSy9bAYjalSkvaBJ8Gb9N0AvI=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBoZudLpMcwtNilm5pwvq/VotTB+8LRm31sJ0y5T3eQ e+mAJYqJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCaGbnSwAKCRBM4MiGSL8RymokD/ 9SpfxpyDr/v/zYpgqfUHtq/bQVt3dyfWDFkTi3dW/Zts8A9eXWlKOCu390Tv7/AutTdHy6jc1S9tr+ HiYBV65A2GXaiCQGTplGvCwJPp046Wct9GCH1lVBslDURQrtUV37aNh2AQiYnKBD9EpFMCAJyQ3DYc t8BWHncCaLCqdMQbGAxMqtrFZL8V4wTiDOjvmaPl80pYfiGhfKc6zFfo1jA6MsNq2QsTJ0xHxDxcOe 5aeTybh5qn9XzIKTldcYRrwTyWSPliX1BcEgAXdZ7kPBgZ5TL/tMm4FHAla42Gx9eAmlUhq5l2Rywm mkd7Eicr2rtYAbx/AqyeNLX+5QNcER37lMFZrHk+dwhZk9ZbQXCwG5XDaz+F4LniPH28ukHwzWivOE QNw5WyxF4CIyxtkcTpC6wZmnYF79MNH+nbBiz+Qp3YcMWMLKPUOoBcJSZpsFbv/4URo2qp8E2bxyBT fLxR0LBgHi/C1MeLmNS6CG6GnIdxvDuxvL/VVeZkw3UEft5+Mt200NDh7pe5zUzgC+sv1T0ZGJme1s 5KSlJEvDoIbr06WxuinbYOQ5US408LjqlP8t6f6mWKKHn+zTxrXR26QFieVnvxbPk/ZKFrnt85E81X qNbsjHWXzKWgLfgeYJi3gBfLN9ZaTaEh76Y6lYmE0wHfEMn8jBViPysj2YtA== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Content-Transfer-Encoding: 8bit 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 Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/core.c | 5 ++++- 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 2dc5b846ae50..833442661742 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -782,7 +782,10 @@ 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 61fdd343d6f5..659b5d133f3e 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2935,9 +2935,16 @@ 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; -- 2.47.1