Re: btrfs restore memory corruption (bug: 82701)

[Marc Dietrich <marvin24@gmx.de>]

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Am Freitag, 22. August 2014, 14:43:45 schrieb Gui Hecheng:
> On Thu, 2014-08-21 at 16:19 +0200, Marc Dietrich wrote:
> > Am Donnerstag, 21. August 2014, 17:52:16 schrieb Gui Hecheng:
> > > On Mon, 2014-08-18 at 11:25 +0200, Marc Dietrich wrote:
> > > > Hi,
> > > > 
> > > > I did a checkout of the latest btrfs progs to repair my damaged
> > > > filesystem.
> > > > Running btrfs restore gives me several failed to inflate: -6 and
> > > > crashes
> > > > with some memory corruption. I ran it again with valgrind and got:
> > > > 
> > > > valgrind --log-file=x2 -v --leak-check=yes btrfs restore /dev/sda9
> > > > /mnt/backup
> > > > 
> > > > ==8528== Memcheck, a memory error detector
> > > > ==8528== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et
> > > > al.
> > > > ==8528== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright
> > > > info
> > > > ==8528== Command: btrfs restore /dev/sda9 /mnt/backup
> > > > ==8528== Parent PID: 8453
> > > > ==8528==
> > > > ==8528== Syscall param pwrite64(buf) points to uninitialised byte(s)
> > > > ==8528==    at 0x59BE3C3: __pwrite_nocancel (in
> > > > /lib64/libpthread-2.18.so)
> > > > ==8528==    by 0x41F22F: search_dir (cmds-restore.c:392)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x4204B8: cmd_restore (cmds-restore.c:1284)
> > > > ==8528==    by 0x4043FE: main (btrfs.c:286)
> > > > ==8528==  Address 0x66956a0 is 7,056 bytes inside a block of size
> > > > 8,192
> > > > alloc'd
> > > > ==8528==    at 0x4C277AB: malloc (in
> > > > /usr/lib64/valgrind/vgpreload_memcheck- amd64-linux.so)
> > > > ==8528==    by 0x41EEAD: search_dir (cmds-restore.c:316)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x4204B8: cmd_restore (cmds-restore.c:1284)
> > > > ==8528==    by 0x4043FE: main (btrfs.c:286)
> > > 
> > > -------------------[snip]---------------------------------
> > > .... leaks ...
> > > ----------------------------------------------------------
>
> For the leak below...
> I've no idea why the @decompress_lzo() is not statisfied with @inbuf
> with the exact size of the disk bytes.
> Or maybe the compressed data had just sufferred damages...
> 
> BTW, when you wrote your data, did that kernel has the following commit
> for btrfs?
> 	commit: 59516f6017c589e7316418fda6128ba8f829a77f

mmh, I used the master branch which is still on 3.14.2 (from k.org).

Ah, there is a development branch on another repo (repo.or.cz). Why oh why?

> 
> If *NO*, then you may try the following and see if it makes any
> difference:
> ---------------------------------------------------------
> diff --git a/cmds-restore.c b/cmds-restore.c
> index dde7de8..ae1ea72 100644
> --- a/cmds-restore.c
> +++ b/cmds-restore.c
> @@ -297,7 +297,7 @@ static int copy_one_extent(struct btrfs_root *root,
> int fd,
>         ram_size = btrfs_file_extent_ram_bytes(leaf, fi);
>         offset = btrfs_file_extent_offset(leaf, fi);
>         num_bytes = btrfs_file_extent_num_bytes(leaf, fi);
> -       size_left = disk_size;
> +       size_left = num_bytes;
>         if (compress == BTRFS_COMPRESS_NONE)
>                 bytenr += offset;
> 
> @@ -376,7 +376,7 @@ again:
>                 goto out;
>         }
> 
> -       ret = decompress(inbuf, outbuf, disk_size, &ram_size, compress);
> +       ret = decompress(inbuf, outbuf, num_bytes, &ram_size, compress);
>         if (ret) {
>                 num_copies =
> btrfs_num_copies(&root->fs_info->mapping_tree,
>                                               bytenr, length);
> ------------------------------------------------------------------------
> *NOTE*: the above is just a trial, it is actually not proper, but please
> don't worry, it does no harm.

well, my restore finished after 1 week (~ 400 GB of compressed data), from 
which 100 GB got lost. It wasn't important data so I'm willing to redo the 
complete restore again if you (or the the btrfs team) is interested in fixing 
these bugs in the near future.

I will upload the latest valgrind log for the finial run to the bugzilla on 
kernel.org (https://bugzilla.kernel.org/show_bug.cgi?id=82701).

I wonder if there is a corrupted btrfs disk image which can be used as a 
reference and which triggers all the current error paths (or maybe several 
images with one error in each one as other projects do). On the other hand, I 
guess this would be a huge pill of work.

Marc



> -Gui
> 
> > ==3007== Invalid read of size 1
> > ==3007==    at 0x57A11B1: lzo1x_decompress_safe (in
> > /usr/lib64/liblzo2.so.2.0.0)
> > ==3007==    by 0x41E2C4: decompress (cmds-restore.c:122)
> > ==3007==    by 0x41F19D: search_dir (cmds-restore.c:378)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==  Address 0x6887774 is 4 bytes after a block of size 4,096 alloc'd
> > ==3007==    at 0x4C277AB: malloc (in
> > /usr/lib64/valgrind/vgpreload_memcheck- amd64-linux.so)
> > ==3007==    by 0x41EE61: search_dir (cmds-restore.c:309)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > ==3007==    by 0x41F8D7: search_dir (cmds-restore.c:895)
> > 
> > Thanks so far!
> > 
> > Marc
> > 
> > > > ==8528== Invalid read of size 2
> > > > ==8528==    at 0x4C2BFA0: memcpy@@GLIBC_2.14 (in
> > > > /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> > > > ==8528==    by 0x43818F: read_extent_buffer (string3.h:51)
> > > > ==8528==    by 0x41EC66: search_dir (cmds-restore.c:233)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x4204B8: cmd_restore (cmds-restore.c:1284)
> > > > ==8528==    by 0x4043FE: main (btrfs.c:286)
> > > > ==8528==  Address 0x6b0bfb8 is 632 bytes inside a block of size 4,224
> > > > free'd ==8528==    at 0x4C28ADC: free (in
> > > > /usr/lib64/valgrind/vgpreload_memcheck- amd64-linux.so)
> > > > ==8528==    by 0x437895: free_extent_buffer (extent_io.c:618)
> > > > ==8528==    by 0x4261CA: btrfs_release_path (ctree.c:61)
> > > > ==8528==    by 0x426212: btrfs_free_path (ctree.c:51)
> > > > ==8528==    by 0x41F93B: search_dir (cmds-restore.c:911)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==
> > > > ==8528== Invalid read of size 2
> > > > ==8528==    at 0x4C2BFB3: memcpy@@GLIBC_2.14 (in
> > > > /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> > > > ==8528==    by 0x43818F: read_extent_buffer (string3.h:51)
> > > > ==8528==    by 0x41EC66: search_dir (cmds-restore.c:233)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x4204B8: cmd_restore (cmds-restore.c:1284)
> > > > ==8528==    by 0x4043FE: main (btrfs.c:286)
> > > > ==8528==  Address 0x6b0bfb4 is 628 bytes inside a block of size 4,224
> > > > free'd ==8528==    at 0x4C28ADC: free (in
> > > > /usr/lib64/valgrind/vgpreload_memcheck- amd64-linux.so)
> > > > ==8528==    by 0x437895: free_extent_buffer (extent_io.c:618)
> > > > ==8528==    by 0x4261CA: btrfs_release_path (ctree.c:61)
> > > > ==8528==    by 0x426212: btrfs_free_path (ctree.c:51)
> > > > ==8528==    by 0x41F93B: search_dir (cmds-restore.c:911)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==    by 0x41F8D0: search_dir (cmds-restore.c:895)
> > > > ==8528==
> > > > ==8528==
> > > > ==8528== HEAP SUMMARY:
> > > > ==8528==     in use at exit: 0 bytes in 0 blocks
> > > > ==8528==   total heap usage: 260,452 allocs, 260,452 frees,
> > > > 278,189,550
> > > > bytes allocated
> > > > ==8528==
> > > > ==8528== All heap blocks were freed -- no leaks are possible
> > > > ==8528==
> > > > ==8528== For counts of detected and suppressed errors, rerun with: -v
> > > > ==8528== Use --track-origins=yes to see where uninitialised values
> > > > come
> > > > from ==8528== ERROR SUMMARY: 16597 errors from 7 contexts (suppressed:
> > > > 2
> > > > from 2)
> > > > 
> > > > see: https://bugzilla.kernel.org/show_bug.cgi?id=82701
> > > > 
> > > > Marc
> > > > 
> > > > p.s.
> > > > 
> > > > I wonder if this list should be autosubscribed to btrfs related bugs
> > > > 
> > > > --
> > > > To unsubscribe from this list: send the line "unsubscribe linux-btrfs"
> > > > in
> > > > the body of a message to majordomo@vger.kernel.org
> > > > More majordomo info at  http://vger.kernel.org/majordomo-info.html

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