- security fix from upstream

diff --git a/kernel-small_fixes.patch b/kernel-small_fixes.patch
index d4b603499b05f64e51b96e527678c26a94700ef8..5c9ff24b1b0f50dc54988023210ad336a9bb7890 100644 (file)
--- a/kernel-small_fixes.patch
+++ b/kernel-small_fixes.patch
@@ -26,3 +26,49 @@
                                exit
                        fi
                done
+From 8358b02bf67d3a5d8a825070e1aa73f25fb2e4c7 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()
+
+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>
+---
+ kernel/bpf/verifier.c | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
+index 618ef77..db2574e 100644
+--- a/kernel/bpf/verifier.c
++++ b/kernel/bpf/verifier.c
+@@ -2030,7 +2030,6 @@ 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);
+                       }
+ 
+-- 
+cgit v0.12
+