From d45ed4a4e33ae103053c0a53d280014e7101bb5c Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 4 Oct 2013 00:14:06 -0700 Subject: [PATCH] net: fix unsafe set_memory_rw from softirq on x86 system with net.core.bpf_jit_enable = 1 sudo tcpdump -i eth1 'tcp port 22' causes the warning: [ 56.766097] Possible unsafe locking scenario: [ 56.766097] [ 56.780146] CPU0 [ 56.786807] ---- [ 56.793188] lock(&(&vb->lock)->rlock); [ 56.799593] [ 56.805889] lock(&(&vb->lock)->rlock); [ 56.812266] [ 56.812266] *** DEADLOCK *** [ 56.812266] [ 56.830670] 1 lock held by ksoftirqd/1/13: [ 56.836838] #0: (rcu_read_lock){.+.+..}, at: [] vm_unmap_aliases+0x8c/0x380 [ 56.849757] [ 56.849757] stack backtrace: [ 56.862194] CPU: 1 PID: 13 Comm: ksoftirqd/1 Not tainted 3.12.0-rc3+ #45 [ 56.868721] Hardware name: System manufacturer System Product Name/P8Z77 WS, BIOS 3007 07/26/2012 [ 56.882004] ffffffff821944c0 ffff88080bbdb8c8 ffffffff8175a145 0000000000000007 [ 56.895630] ffff88080bbd5f40 ffff88080bbdb928 ffffffff81755b14 0000000000000001 [ 56.909313] ffff880800000001 ffff880800000000 ffffffff8101178f 0000000000000001 [ 56.923006] Call Trace: [ 56.929532] [] dump_stack+0x55/0x76 [ 56.936067] [] print_usage_bug+0x1f7/0x208 [ 56.942445] [] ? save_stack_trace+0x2f/0x50 [ 56.948932] [] ? check_usage_backwards+0x150/0x150 [ 56.955470] [] mark_lock+0x282/0x2c0 [ 56.961945] [] __lock_acquire+0x45d/0x1d50 [ 56.968474] [] ? __lock_acquire+0x2de/0x1d50 [ 56.975140] [] ? cpumask_next_and+0x55/0x90 [ 56.981942] [] lock_acquire+0x92/0x1d0 [ 56.988745] [] ? vm_unmap_aliases+0x16a/0x380 [ 56.995619] [] _raw_spin_lock+0x41/0x50 [ 57.002493] [] ? vm_unmap_aliases+0x16a/0x380 [ 57.009447] [] vm_unmap_aliases+0x16a/0x380 [ 57.016477] [] ? vm_unmap_aliases+0x8c/0x380 [ 57.023607] [] change_page_attr_set_clr+0xc0/0x460 [ 57.030818] [] ? trace_hardirqs_on+0xd/0x10 [ 57.037896] [] ? kmem_cache_free+0xb0/0x2b0 [ 57.044789] [] ? free_object_rcu+0x93/0xa0 [ 57.051720] [] set_memory_rw+0x2f/0x40 [ 57.058727] [] bpf_jit_free+0x2c/0x40 [ 57.065577] [] sk_filter_release_rcu+0x1a/0x30 [ 57.072338] [] rcu_process_callbacks+0x202/0x7c0 [ 57.078962] [] __do_softirq+0xf7/0x3f0 [ 57.085373] [] run_ksoftirqd+0x35/0x70 cannot reuse jited filter memory, since it's readonly, so use original bpf insns memory to hold work_struct defer kfree of sk_filter until jit completed freeing tested on x86_64 and i386 Signed-off-by: Alexei Starovoitov Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- arch/arm/net/bpf_jit_32.c | 1 + arch/powerpc/net/bpf_jit_comp.c | 1 + arch/s390/net/bpf_jit_comp.c | 4 +++- arch/sparc/net/bpf_jit_comp.c | 1 + arch/x86/net/bpf_jit_comp.c | 18 +++++++++++++----- include/linux/filter.h | 15 +++++++++++---- include/net/sock.h | 6 ++---- net/core/filter.c | 8 ++++---- 8 files changed, 36 insertions(+), 18 deletions(-) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index f50d223a0bd3..99b44e0e8d86 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -930,4 +930,5 @@ void bpf_jit_free(struct sk_filter *fp) { if (fp->bpf_func != sk_run_filter) module_free(NULL, fp->bpf_func); + kfree(fp); } diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index bf56e33f8257..2345bdb4d917 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -691,4 +691,5 @@ void bpf_jit_free(struct sk_filter *fp) { if (fp->bpf_func != sk_run_filter) module_free(NULL, fp->bpf_func); + kfree(fp); } diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 709239285869..a5df511e27a2 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -881,7 +881,9 @@ void bpf_jit_free(struct sk_filter *fp) struct bpf_binary_header *header = (void *)addr; if (fp->bpf_func == sk_run_filter) - return; + goto free_filter; set_memory_rw(addr, header->pages); module_free(NULL, header); +free_filter: + kfree(fp); } diff --git a/arch/sparc/net/bpf_jit_comp.c b/arch/sparc/net/bpf_jit_comp.c index 9c7be59e6f5a..218b6b23c378 100644 --- a/arch/sparc/net/bpf_jit_comp.c +++ b/arch/sparc/net/bpf_jit_comp.c @@ -808,4 +808,5 @@ void bpf_jit_free(struct sk_filter *fp) { if (fp->bpf_func != sk_run_filter) module_free(NULL, fp->bpf_func); + kfree(fp); } diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 79c216aa0e2b..516593e1ce33 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -772,13 +772,21 @@ cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i]; return; } +static void bpf_jit_free_deferred(struct work_struct *work) +{ + struct sk_filter *fp = container_of(work, struct sk_filter, work); + unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK; + struct bpf_binary_header *header = (void *)addr; + + set_memory_rw(addr, header->pages); + module_free(NULL, header); + kfree(fp); +} + void bpf_jit_free(struct sk_filter *fp) { if (fp->bpf_func != sk_run_filter) { - unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK; - struct bpf_binary_header *header = (void *)addr; - - set_memory_rw(addr, header->pages); - module_free(NULL, header); + INIT_WORK(&fp->work, bpf_jit_free_deferred); + schedule_work(&fp->work); } } diff --git a/include/linux/filter.h b/include/linux/filter.h index a6ac84871d6d..ff4e40cd45b1 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -6,6 +6,7 @@ #include #include +#include #include #ifdef CONFIG_COMPAT @@ -25,15 +26,19 @@ struct sk_filter { atomic_t refcnt; unsigned int len; /* Number of filter blocks */ + struct rcu_head rcu; unsigned int (*bpf_func)(const struct sk_buff *skb, const struct sock_filter *filter); - struct rcu_head rcu; - struct sock_filter insns[0]; + union { + struct sock_filter insns[0]; + struct work_struct work; + }; }; -static inline unsigned int sk_filter_len(const struct sk_filter *fp) +static inline unsigned int sk_filter_size(unsigned int proglen) { - return fp->len * sizeof(struct sock_filter) + sizeof(*fp); + return max(sizeof(struct sk_filter), + offsetof(struct sk_filter, insns[proglen])); } extern int sk_filter(struct sock *sk, struct sk_buff *skb); @@ -67,11 +72,13 @@ static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen, } #define SK_RUN_FILTER(FILTER, SKB) (*FILTER->bpf_func)(SKB, FILTER->insns) #else +#include static inline void bpf_jit_compile(struct sk_filter *fp) { } static inline void bpf_jit_free(struct sk_filter *fp) { + kfree(fp); } #define SK_RUN_FILTER(FILTER, SKB) sk_run_filter(SKB, FILTER->insns) #endif diff --git a/include/net/sock.h b/include/net/sock.h index 1d37a8086bed..808cbc2ec6c1 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1630,16 +1630,14 @@ static inline void sk_filter_release(struct sk_filter *fp) static inline void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp) { - unsigned int size = sk_filter_len(fp); - - atomic_sub(size, &sk->sk_omem_alloc); + atomic_sub(sk_filter_size(fp->len), &sk->sk_omem_alloc); sk_filter_release(fp); } static inline void sk_filter_charge(struct sock *sk, struct sk_filter *fp) { atomic_inc(&fp->refcnt); - atomic_add(sk_filter_len(fp), &sk->sk_omem_alloc); + atomic_add(sk_filter_size(fp->len), &sk->sk_omem_alloc); } /* diff --git a/net/core/filter.c b/net/core/filter.c index 6438f29ff266..01b780856db2 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -644,7 +644,6 @@ void sk_filter_release_rcu(struct rcu_head *rcu) struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); bpf_jit_free(fp); - kfree(fp); } EXPORT_SYMBOL(sk_filter_release_rcu); @@ -683,7 +682,7 @@ int sk_unattached_filter_create(struct sk_filter **pfp, if (fprog->filter == NULL) return -EINVAL; - fp = kmalloc(fsize + sizeof(*fp), GFP_KERNEL); + fp = kmalloc(sk_filter_size(fprog->len), GFP_KERNEL); if (!fp) return -ENOMEM; memcpy(fp->insns, fprog->filter, fsize); @@ -723,6 +722,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) { struct sk_filter *fp, *old_fp; unsigned int fsize = sizeof(struct sock_filter) * fprog->len; + unsigned int sk_fsize = sk_filter_size(fprog->len); int err; if (sock_flag(sk, SOCK_FILTER_LOCKED)) @@ -732,11 +732,11 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) if (fprog->filter == NULL) return -EINVAL; - fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); + fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL); if (!fp) return -ENOMEM; if (copy_from_user(fp->insns, fprog->filter, fsize)) { - sock_kfree_s(sk, fp, fsize+sizeof(*fp)); + sock_kfree_s(sk, fp, sk_fsize); return -EFAULT; }