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| author | Amir Goldstein <amir73il@gmail.com> | 2020-05-23 16:21:55 +0300 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2020-06-02 23:20:25 +0300 |
| commit | 522f6e6cba6880a038e2bd88e10390b84cd3febd (patch) | |
| tree | 961e5f4e11905dae3156031fe925bc4b327cb3ae /fs/overlayfs | |
| parent | 144da23beab87b27992e5e1b41bd954de0bf2581 (diff) | |
| download | linux-522f6e6cba6880a038e2bd88e10390b84cd3febd.tar.xz | |
ovl: fix out of bounds access warning in ovl_check_fb_len()
syzbot reported out of bounds memory access from open_by_handle_at()
with a crafted file handle that looks like this:
{ .handle_bytes = 2, .handle_type = OVL_FILEID_V1 }
handle_bytes gets rounded down to 0 and we end up calling:
ovl_check_fh_len(fh, 0) => ovl_check_fb_len(fh + 3, -3)
But fh buffer is only 2 bytes long, so accessing struct ovl_fb at
fh + 3 is illegal.
Fixes: cbe7fba8edfc ("ovl: make sure that real fid is 32bit aligned in memory")
Reported-and-tested-by: syzbot+61958888b1c60361a791@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org> # v5.5
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/overlayfs.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 76747f5b0517..ffbb57b2d7f6 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -355,6 +355,9 @@ int ovl_check_fb_len(struct ovl_fb *fb, int fb_len); static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len) { + if (fh_len < sizeof(struct ovl_fh)) + return -EINVAL; + return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET); } |