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authorAlexei Starovoitov <ast@plumgrid.com>2015-01-22 17:11:08 -0800
committerDavid S. Miller <davem@davemloft.net>2015-01-26 17:20:40 -0800
commit8ebe667c41e054384df19f2f382bc415badfaee1 (patch)
tree45c41bc68790f63aba66c5ab65492a89423587db /kernel/bpf
parent600ddd6825543962fb807884169e57b580dba208 (diff)
bpf: rcu lock must not be held when calling copy_to_user()
BUG: sleeping function called from invalid context at mm/memory.c:3732 in_atomic(): 0, irqs_disabled(): 0, pid: 671, name: test_maps 1 lock held by test_maps/671: #0: (rcu_read_lock){......}, at: [<0000000000264190>] map_lookup_elem+0xe8/0x260 Call Trace: ([<0000000000115b7e>] show_trace+0x12e/0x150) [<0000000000115c40>] show_stack+0xa0/0x100 [<00000000009b163c>] dump_stack+0x74/0xc8 [<000000000017424a>] ___might_sleep+0x23a/0x248 [<00000000002b58e8>] might_fault+0x70/0xe8 [<0000000000264230>] map_lookup_elem+0x188/0x260 [<0000000000264716>] SyS_bpf+0x20e/0x840 Fix it by allocating temporary buffer to store map element value. Fixes: db20fd2b0108 ("bpf: add lookup/update/delete/iterate methods to BPF maps") Reported-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Acked-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/syscall.c25
1 files changed, 17 insertions, 8 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 088ac0b1b106..536edc2be307 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -150,7 +150,7 @@ static int map_lookup_elem(union bpf_attr *attr)
int ufd = attr->map_fd;
struct fd f = fdget(ufd);
struct bpf_map *map;
- void *key, *value;
+ void *key, *value, *ptr;
int err;
if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
@@ -169,20 +169,29 @@ static int map_lookup_elem(union bpf_attr *attr)
if (copy_from_user(key, ukey, map->key_size) != 0)
goto free_key;
- err = -ENOENT;
- rcu_read_lock();
- value = map->ops->map_lookup_elem(map, key);
+ err = -ENOMEM;
+ value = kmalloc(map->value_size, GFP_USER);
if (!value)
- goto err_unlock;
+ goto free_key;
+
+ rcu_read_lock();
+ ptr = map->ops->map_lookup_elem(map, key);
+ if (ptr)
+ memcpy(value, ptr, map->value_size);
+ rcu_read_unlock();
+
+ err = -ENOENT;
+ if (!ptr)
+ goto free_value;
err = -EFAULT;
if (copy_to_user(uvalue, value, map->value_size) != 0)
- goto err_unlock;
+ goto free_value;
err = 0;
-err_unlock:
- rcu_read_unlock();
+free_value:
+ kfree(value);
free_key:
kfree(key);
err_put: