staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

[ Upstream commit 97fbfef6bd597888485b653175fb846c6998b60c ]

vfs_llseek will check whether the file mode has
FMODE_LSEEK, no return failure. But ashmem can be
lseek, so add FMODE_LSEEK to ashmem file.

Comment From Greg Hackmann:
	ashmem_llseek() passes the llseek() call through to the backing
	shmem file.  91360b02ab48 ("ashmem: use vfs_llseek()") changed
	this from directly calling the file's llseek() op into a VFS
	layer call.  This also adds a check for the FMODE_LSEEK bit, so
	without that bit ashmem_llseek() now always fails with -ESPIPE.

Fixes: 91360b02ab48 ("ashmem: use vfs_llseek()")
Signed-off-by: Shuxiao Zhang <zhangshuxiao@xiaomi.com>
Tested-by: Greg Hackmann <ghackmann@google.com>
Cc: stable <stable@vger.kernel.org> # 3.18+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index c5c037ccf32cc0097f25fe16ddc7848cbd41e547..7dd6bde4f3252c2767785e216041dbbdd751c0fd 100644 (file)
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -392,6 +392,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
                        ret = PTR_ERR(vmfile);
                        goto out;
                }
+               vmfile->f_mode |= FMODE_LSEEK;
                asma->file = vmfile;
        }
        get_file(asma->file);