| Message ID | 1464112408-1002-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b1f68c2..9718319 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1896,7 +1896,6 @@ 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); }
This is a note to let you know that I have just added a patch titled bpf: fix double-fdput in replace_map_fd_with_map_ptr() to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From be3db2d4c5507ad1fbacbf502dab1b8057ffd69e Mon Sep 17 00:00:00 2001 From: Jann Horn <jannh@google.com> Date: Tue, 26 Apr 2016 22:26:26 +0200 Subject: 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: Kamal Mostafa <kamal@canonical.com> --- kernel/bpf/verifier.c | 1 - 1 file changed, 1 deletion(-) -- 2.7.4