diff options
| author | Jann Horn <jannh@google.com> | 2016-04-26 22:26:26 +0200 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-07-10 23:07:22 -0400 |
| commit | 7b6460337ed23f3b29958e853f7d1f191bfd844d (patch) | |
| tree | 535e8148187d87c3ae40a3ef590fe393fe7ce74b /kernel | |
| parent | eeee948a652e9ee02643bf031cd613339ccc6864 (diff) | |
bpf: fix double-fdput in replace_map_fd_with_map_ptr()
[ Upstream commit 8358b02bf67d3a5d8a825070e1aa73f25fb2e4c7 ]
When bpf(BPF_PROG_LOAD, ...) was invoked with a BPF program whose bytecode
references a non-map file descriptor as a map file descriptor, the error
handling code called fdput() twice instead of once (in __bpf_map_get() and
in replace_map_fd_with_map_ptr()). If the file descriptor table of the
current task is shared, this causes f_count to be decremented too much,
allowing the struct file to be freed while it is still in use
(use-after-free). This can be exploited to gain root privileges by an
unprivileged user.
This bug was introduced in
commit 0246e64d9a5f ("bpf: handle pseudo BPF_LD_IMM64 insn"), but is only
exploitable since
commit 1be7f75d1668 ("bpf: enable non-root eBPF programs") because
previously, CAP_SYS_ADMIN was required to reach the vulnerable code.
(posted publicly according to request by maintainer)
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index dd16d1993c04..efd143dcedf1 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1865,7 +1865,6 @@ static int replace_map_fd_with_map_ptr(struct verifier_env *env) if (IS_ERR(map)) { verbose("fd %d is not pointing to valid bpf_map\n", insn->imm); - fdput(f); return PTR_ERR(map); } |