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authorKP Singh <kpsingh@kernel.org>2021-01-12 07:55:24 +0000
committerDaniel Borkmann <daniel@iogearbox.net>2021-01-12 16:07:56 +0100
commit1a9c72ad4c26821e215a396167c14959cf24a7f1 (patch)
tree6ad0a408dc69441a89b2c3feae81e7a090b0e135 /kernel/bpf/bpf_inode_storage.c
parent5541075a348b6ca6ac668653f7d2c423ae8e00b6 (diff)
bpf: Local storage helpers should check nullness of owner ptr passed
The verifier allows ARG_PTR_TO_BTF_ID helper arguments to be NULL, so helper implementations need to check this before dereferencing them. This was already fixed for the socket storage helpers but not for task and inode. The issue can be reproduced by attaching an LSM program to inode_rename hook (called when moving files) which tries to get the inode of the new file without checking for its nullness and then trying to move an existing file to a new path: mv existing_file new_file_does_not_exist The report including the sample program and the steps for reproducing the bug: https://lore.kernel.org/bpf/CANaYP3HWkH91SN=wTNO9FL_2ztHfqcXKX38SSE-JJ2voh+vssw@mail.gmail.com Fixes: 4cf1bc1f1045 ("bpf: Implement task local storage") Fixes: 8ea636848aca ("bpf: Implement bpf_local_storage for inodes") Reported-by: Gilad Reti <gilad.reti@gmail.com> Signed-off-by: KP Singh <kpsingh@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210112075525.256820-3-kpsingh@kernel.org
Diffstat (limited to 'kernel/bpf/bpf_inode_storage.c')
-rw-r--r--kernel/bpf/bpf_inode_storage.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c
index 6edff97ad594..dbc1dbdd2cbf 100644
--- a/kernel/bpf/bpf_inode_storage.c
+++ b/kernel/bpf/bpf_inode_storage.c
@@ -176,7 +176,7 @@ BPF_CALL_4(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
* bpf_local_storage_update expects the owner to have a
* valid storage pointer.
*/
- if (!inode_storage_ptr(inode))
+ if (!inode || !inode_storage_ptr(inode))
return (unsigned long)NULL;
sdata = inode_storage_lookup(inode, map, true);
@@ -200,6 +200,9 @@ BPF_CALL_4(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
BPF_CALL_2(bpf_inode_storage_delete,
struct bpf_map *, map, struct inode *, inode)
{
+ if (!inode)
+ return -EINVAL;
+
/* This helper must only called from where the inode is gurranteed
* to have a refcount and cannot be freed.
*/