On Mon, Dec 04, 2023 at 12:11:28PM +0100, Peter Zijlstra wrote: > On Mon, Dec 04, 2023 at 10:13:34AM +0100, Peter Zijlstra wrote: > > > > Just running test_progs it splats right away: > > > > > > [ 74.047757] kmemleak: Found object by alias at 0xffffffffa0001d80 > > > [ 74.048272] CPU: 14 PID: 104 Comm: kworker/14:0 Tainted: G W > > > O 6.7.0-rc3-00702-g41c30fec304d-dirty #5241 > > > [ 74.049118] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > > > BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 > > > [ 74.050042] Workqueue: events bpf_prog_free_deferred > > > [ 74.050448] Call Trace: > > > [ 74.050663] <TASK> > > > [ 74.050841] dump_stack_lvl+0x55/0x80 > > > [ 74.051141] __find_and_remove_object+0xdb/0x110 > > > [ 74.051521] kmemleak_free+0x41/0x70 > > > [ 74.051828] vfree+0x36/0x130 > > > > Durr, I'll see if I can get that stuff running locally, and otherwise > > play with the robot as you suggested. Thanks! > > I think it is bpf_jit_binary_pack_hdr(), which is using prog->bpf_func > as a start address for the image, instead of jit_data->image. > > This used to be true, but now it's offset. > > Let me see what to do about that... Not the prettiest of things, but the below seems to make the thing happy... --- diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 196cc1481dec..f4357c3211bc 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -3024,6 +3024,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) prog->bpf_func = (void *)image + ctx.prog_offset; prog->jited = 1; prog->jited_len = proglen - ctx.prog_offset; + prog->aux->cfi_offset = ctx.prog_offset; } else { prog = orig_prog; } @@ -3078,6 +3079,7 @@ void bpf_jit_free(struct bpf_prog *prog) kvfree(jit_data->addrs); kfree(jit_data); } + prog->bpf_func = (void *)prog->bpf_func - prog->aux->cfi_offset; hdr = bpf_jit_binary_pack_hdr(prog); bpf_jit_binary_pack_free(hdr, NULL); WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(prog)); diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 8b725776e70a..e5fa0852a20f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1483,6 +1483,7 @@ struct bpf_prog_aux { struct work_struct work; struct rcu_head rcu; }; + u32 cfi_offset; }; struct bpf_prog { diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 5c84a935ba63..763742f4740f 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -121,6 +121,9 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag #endif INIT_LIST_HEAD_RCU(&fp->aux->ksym.lnode); +#ifdef CONFIG_FINEIBT + INIT_LIST_HEAD_RCU(&fp->aux->ksym_prefix.lnode); +#endif mutex_init(&fp->aux->used_maps_mutex); mutex_init(&fp->aux->dst_mutex); @@ -709,6 +712,8 @@ void bpf_prog_kallsyms_del(struct bpf_prog *fp) bpf_ksym_del(&fp->aux->ksym); #ifdef CONFIG_FINEIBT + if (cfi_mode != CFI_FINEIBT) + return; bpf_ksym_del(&fp->aux->ksym_prefix); #endif }