vfs: missed source of ->f_pos races

commit 0e665d5d1125f9f4ccff56a75e814f10f88861a2 upstream.

compat_sys_{read,write}v() need the same "pass a copy of file->f_pos" thing
as sys_{read,write}{,v}().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/fs/compat.c b/fs/compat.c
index 633e63c32aa746bac8abc2f4fcd25dfe767b5f48..388555d404bf38f00e35018e4850957eee48b428 100644 (file)
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1231,11 +1231,14 @@ compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec,
        struct file *file;
        int fput_needed;
        ssize_t ret;
+       loff_t pos;
 
        file = fget_light(fd, &fput_needed);
        if (!file)
                return -EBADF;
-       ret = compat_readv(file, vec, vlen, &file->f_pos);
+       pos = file->f_pos;
+       ret = compat_readv(file, vec, vlen, &pos);
+       file->f_pos = pos;
        fput_light(file, fput_needed);
        return ret;
 }
@@ -1288,11 +1291,14 @@ compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec,
        struct file *file;
        int fput_needed;
        ssize_t ret;
+       loff_t pos;
 
        file = fget_light(fd, &fput_needed);
        if (!file)
                return -EBADF;
-       ret = compat_writev(file, vec, vlen, &file->f_pos);
+       pos = file->f_pos;
+       ret = compat_writev(file, vec, vlen, &pos);
+       file->f_pos = pos;
        fput_light(file, fput_needed);
        return ret;
 }