[PATCH 3.18 068/145] staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

Greg Kroah-Hartman
2017-04-16T11:14:10Z

From: Shuxiao Zhang <zhangshuxiao@xiaomi.com>

commit 97fbfef6bd597888485b653175fb846c6998b60c upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/android/ashmem.c | 1 +
1 file changed, 1 insertion(+)

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