lkml.org 
[lkml]   [2015]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: Endless getdents() in vfat filesystem
From
On Sat, Nov 14, 2015 at 2:19 AM, Vegard Nossum <vegard.nossum@oracle.com> wrote:
> Hi,
>
> Using the attached disk image I observe that getdents() never returns
> the end of the directory, i.e. mounting the disk image on a loopback
> device and running 'ls' under strace shows an endless stream of:
>
> getdents(3, /* 2 entries */, 32768) = 48
> getdents(3, /* 2 entries */, 32768) = 48
> getdents(3, /* 2 entries */, 32768) = 48
> ...

Please more details. Is this image hand crafted?
If not, how has it been created? Is is supposed to work?

From a quick look it seems as the root directory is bad but we report
progress in ->iterate.
ctx->pos is 2, we set it back to 0, because of the faked dot entries.
but fat_get_entry() did not make any progress and we report 0 back to VFS.
So, VFS sees progress and the game continues.

Does the attached patch help?

--
Thanks,
//richard
diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 4afc4d9..7f66a38 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -586,8 +586,12 @@ static int __fat_readdir(struct inode *inode, struct file *file,

bh = NULL;
get_new:
- if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
+ if (fat_get_entry(inode, &cpos, &bh, &de) == -1) {
+ if (cpos == 0)
+ cpos = 2;
+
goto end_of_dir;
+ }
parse_record:
nr_slots = 0;
/*
\
 
 \ /
  Last update: 2015-11-14 11:41    [W:0.060 / U:0.764 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site