| From | Paul Gortmaker <> | Subject | [34-longterm 064/196] UBIFS: fix oops when R/O file-system is fsync'ed | Date | Mon, 12 Mar 2012 20:19:37 -0400 |
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From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
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 <Reuben.Dowle@navico.com> for reporting about this issue.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Reported-by: Reuben Dowle <Reuben.Dowle@navico.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- fs/ubifs/file.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index 5692cf7..1a411fd 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -1312,6 +1312,9 @@ int ubifs_fsync(struct file *file, struct dentry *dentry, int datasync) 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. -- 1.7.9.3
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