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Re: [PATCH] xfsprogs/quota: fix NULL pointer dereference in report_f

To: Jeff Liu <jeff.liu@xxxxxxxxxx>
Subject: Re: [PATCH] xfsprogs/quota: fix NULL pointer dereference in report_f
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Thu, 14 Nov 2013 06:09:16 -0800
Cc: "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <52849CC5.10109@xxxxxxxxxx>
References: <52849CC5.10109@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, Nov 14, 2013 at 05:49:57PM +0800, Jeff Liu wrote:
> From: Jie Liu <jeff.liu@xxxxxxxxxx>
> 
> Run xfs_quota report against an invalid XFS path without desired quota
> limitation is enabled will hit SEGSEGV as fs_path is uninitialized, e.g.
> 
> # xfs_quota -xc 'report -up' /invalid_path
> xfs_quota: cannot setup path for mount /invalid_path: No such file or 
> directory
> Segmentation fault (core dumped)
> 
> (gdb) r -xc 'report -up' /invalid_path
> xfs_quota: cannot setup path for mount /invalid_path: No such file or 
> directory
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x0000000000408b4d in report_f (argc=2, argv=0x105ea70) at report.c:627
> 627                   else if (fs_path->fs_flags & FS_MOUNT_POINT)
> 
> This patch fix report_f() to only do report if the fs_path is initialized.

quot_f in quot.c and various functions in state.c seem to have the same
issue, and need fixing as well.

I'd love to avoid having to expose fs_path as a global and just have a
few safe accessors:

char *global_fsname(void)
{
        return fs_path ? fs_path->fs_name : NULL;
}

char *global_dir(void)
{
        return fs_path ? fs_path->fs_dir : NULL;
}

char *global_mountpoint(void)
{
        if (fs_path && (fs_path->fs_flags & FS_MOUNT_POINT))
                return fs_path->fs_dir;
        return NULL;
}

Together with moving a bit of code from quota/init.c to libxcmd/path.c
that should allow mkaing fs_path and fs_table static there.


I'd also really love to see a regression test for xfstests.

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