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Subject[40/70] UBIFS: fix oops when R/O file-system is fsynced
2.6.38-stable review patch.  If anyone has any objections, please let us know.


From: Artem Bityutskiy <>

commit 78530bf7f2559b317c04991b52217c1608d5a58d upstream.

This patch fixes severe UBIFS bug: UBIFS oopses when we 'fsync()' an
file on R/O-mounter file-system. We (the UBIFS authors) incorrectly
thought that VFS would not propagate 'fsync()' down to the file-system
if it is read-only, but this is not the case.

It is easy to exploit this bug using the following simple perl script:

use strict;
use File::Sync qw(fsync sync);

die "File path is not specified" if not defined $ARGV[0];
my $path = $ARGV[0];

open FILE, "<", "$path" or die "Cannot open $path: $!";
fsync(\*FILE) or die "cannot fsync $path: $!";
close FILE or die "Cannot close $path: $!";

Thanks to Reuben Dowle <> for reporting about this

Signed-off-by: Artem Bityutskiy <>
Reported-by: Reuben Dowle <>
Signed-off-by: Greg Kroah-Hartman <>

fs/ubifs/file.c | 3 +++
1 file changed, 3 insertions(+)

--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1309,6 +1309,9 @@ int ubifs_fsync(struct file *file, int d

dbg_gen("syncing inode %lu", inode->i_ino);

+ if (inode->i_sb->s_flags & MS_RDONLY)
+ return 0;
* VFS has already synchronized dirty pages for this inode. Synchronize
* the inode unless this is a 'datasync()' call.

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