| Message ID | 1320113103-27406-1-git-send-email-guaneryu@gmail.com |
|---|---|
| State | Accepted, archived |
| Headers | show |
On 2011-10-31, at 8:05 PM, Eryu Guan wrote: > I hit a J_ASSERT(blocknr != 0) failure in cleanup_journal_tail() when > mounting a fsfuzzed ext3 image. It turns out that the corrupted ext3 > image has s_first = 0 in journal superblock, and the 0 is passed to > journal->j_head in journal_reset(), then to blocknr in > cleanup_journal_tail(), in the end the J_ASSERT failed. > > So validate s_first after reading journal superblock from disk in > journal_get_superblock() to ensure s_first is valid. > > The following script could reproduce it: > > fstype=ext3 > blocksize=1024 > img=$fstype.img > offset=0 > found=0 > magic="c0 3b 39 98" > > dd if=/dev/zero of=$img bs=1M count=8 > mkfs -t $fstype -b $blocksize -F $img > filesize=`stat -c %s $img` > while [ $offset -lt $filesize ] > do > if od -j $offset -N 4 -t x1 $img | grep -i "$magic";then > echo "Found journal: $offset" > found=1 > break > fi > offset=`echo "$offset+$blocksize" | bc` > done > > if [ $found -ne 1 ];then > echo "Magic \"$magic\" not found" > exit 1 > fi > > dd if=/dev/zero of=$img seek=$(($offset+23)) conv=notrunc bs=1 count=1 > > mkdir -p ./mnt > mount -o loop $img ./mnt > > Cc: Jan Kara <jack@suse.cz> > Cc: "Theodore Ts'o" <tytso@mit.edu> > Signed-off-by: Eryu Guan <guaneryu@gmail.com> > --- > fs/jbd/journal.c | 8 ++++++++ > fs/jbd2/journal.c | 8 ++++++++ > 2 files changed, 16 insertions(+), 0 deletions(-) > > diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c > index 9fe061f..0c401de 100644 > --- a/fs/jbd/journal.c > +++ b/fs/jbd/journal.c > @@ -1135,6 +1135,14 @@ static int journal_get_superblock(journal_t *journal) > goto out; > } > > + if (be32_to_cpu(sb->s_first) == 0 || > + be32_to_cpu(sb->s_first) >= journal->j_maxlen) { (style) Please fix the indenting to align with '(' on previous line. > + printk(KERN_WARNING > + "JBD: Invalid start block of journal: %u\n", > + be32_to_cpu(sb->s_first)); > + goto out; > + } > + > return 0; > > out: > diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c > index f24df13..e2d0e13 100644 > --- a/fs/jbd2/journal.c > +++ b/fs/jbd2/journal.c > @@ -1251,6 +1251,14 @@ static int journal_get_superblock(journal_t *journal) > goto out; > } > > + if (be32_to_cpu(sb->s_first) == 0 || > + be32_to_cpu(sb->s_first) >= journal->j_maxlen) { (style) same. > + printk(KERN_WARNING > + "JBD2: Invalid start block of journal: %u\n", > + be32_to_cpu(sb->s_first)); > + goto out; > + } > + > return 0; Looks fine otherwise. Cheers, Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue 01-11-11 10:05:03, Eryu Guan wrote: > I hit a J_ASSERT(blocknr != 0) failure in cleanup_journal_tail() when > mounting a fsfuzzed ext3 image. It turns out that the corrupted ext3 > image has s_first = 0 in journal superblock, and the 0 is passed to > journal->j_head in journal_reset(), then to blocknr in > cleanup_journal_tail(), in the end the J_ASSERT failed. > > So validate s_first after reading journal superblock from disk in > journal_get_superblock() to ensure s_first is valid. > > The following script could reproduce it: > > fstype=ext3 > blocksize=1024 > img=$fstype.img > offset=0 > found=0 > magic="c0 3b 39 98" > > dd if=/dev/zero of=$img bs=1M count=8 > mkfs -t $fstype -b $blocksize -F $img > filesize=`stat -c %s $img` > while [ $offset -lt $filesize ] > do > if od -j $offset -N 4 -t x1 $img | grep -i "$magic";then > echo "Found journal: $offset" > found=1 > break > fi > offset=`echo "$offset+$blocksize" | bc` > done > > if [ $found -ne 1 ];then > echo "Magic \"$magic\" not found" > exit 1 > fi > > dd if=/dev/zero of=$img seek=$(($offset+23)) conv=notrunc bs=1 count=1 > > mkdir -p ./mnt > mount -o loop $img ./mnt Thanks. I've fixed-up the style problems pointed out by Andreas and added the patch to my tree. Honza > > Cc: Jan Kara <jack@suse.cz> > Cc: "Theodore Ts'o" <tytso@mit.edu> > Signed-off-by: Eryu Guan <guaneryu@gmail.com> > --- > fs/jbd/journal.c | 8 ++++++++ > fs/jbd2/journal.c | 8 ++++++++ > 2 files changed, 16 insertions(+), 0 deletions(-) > > diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c > index 9fe061f..0c401de 100644 > --- a/fs/jbd/journal.c > +++ b/fs/jbd/journal.c > @@ -1135,6 +1135,14 @@ static int journal_get_superblock(journal_t *journal) > goto out; > } > > + if (be32_to_cpu(sb->s_first) == 0 || > + be32_to_cpu(sb->s_first) >= journal->j_maxlen) { > + printk(KERN_WARNING > + "JBD: Invalid start block of journal: %u\n", > + be32_to_cpu(sb->s_first)); > + goto out; > + } > + > return 0; > > out: > diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c > index f24df13..e2d0e13 100644 > --- a/fs/jbd2/journal.c > +++ b/fs/jbd2/journal.c > @@ -1251,6 +1251,14 @@ static int journal_get_superblock(journal_t *journal) > goto out; > } > > + if (be32_to_cpu(sb->s_first) == 0 || > + be32_to_cpu(sb->s_first) >= journal->j_maxlen) { > + printk(KERN_WARNING > + "JBD2: Invalid start block of journal: %u\n", > + be32_to_cpu(sb->s_first)); > + goto out; > + } > + > return 0; > > out: > -- > 1.7.7.1 >
On Tue, Nov 01, 2011 at 10:05:03AM +0800, Eryu Guan wrote: > I hit a J_ASSERT(blocknr != 0) failure in cleanup_journal_tail() when > mounting a fsfuzzed ext3 image. It turns out that the corrupted ext3 > image has s_first = 0 in journal superblock, and the 0 is passed to > journal->j_head in journal_reset(), then to blocknr in > cleanup_journal_tail(), in the end the J_ASSERT failed. > > So validate s_first after reading journal superblock from disk in > journal_get_superblock() to ensure s_first is valid. > > ... > > Signed-off-by: Eryu Guan <guaneryu@gmail.com> Thanks, applied. (I took the jbd fixup as well, since it's obvious) - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Nov 01, 2011 at 11:29:55PM +0100, Jan Kara wrote: > Thanks. I've fixed-up the style problems pointed out by Andreas and added > the patch to my tree. Oops, I grabbed it too. How do you want to resolve this? I can just carry the jbd2 change, or I can carry both, or I can let you carry both. Either is fine with me. (And if we both carry it git should do the right thing anyway. :-) - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue 01-11-11 19:16:27, Ted Tso wrote: > On Tue, Nov 01, 2011 at 11:29:55PM +0100, Jan Kara wrote: > > Thanks. I've fixed-up the style problems pointed out by Andreas and added > > the patch to my tree. > > Oops, I grabbed it too. How do you want to resolve this? I can just > carry the jbd2 change, or I can carry both, or I can let you carry > both. Either is fine with me. (And if we both carry it git should do > the right thing anyway. :-) OK, carry it, I'll remove the patch from my tree. Honza
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c index 9fe061f..0c401de 100644 --- a/fs/jbd/journal.c +++ b/fs/jbd/journal.c @@ -1135,6 +1135,14 @@ static int journal_get_superblock(journal_t *journal) goto out; } + if (be32_to_cpu(sb->s_first) == 0 || + be32_to_cpu(sb->s_first) >= journal->j_maxlen) { + printk(KERN_WARNING + "JBD: Invalid start block of journal: %u\n", + be32_to_cpu(sb->s_first)); + goto out; + } + return 0; out: diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index f24df13..e2d0e13 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1251,6 +1251,14 @@ static int journal_get_superblock(journal_t *journal) goto out; } + if (be32_to_cpu(sb->s_first) == 0 || + be32_to_cpu(sb->s_first) >= journal->j_maxlen) { + printk(KERN_WARNING + "JBD2: Invalid start block of journal: %u\n", + be32_to_cpu(sb->s_first)); + goto out; + } + return 0; out:
I hit a J_ASSERT(blocknr != 0) failure in cleanup_journal_tail() when mounting a fsfuzzed ext3 image. It turns out that the corrupted ext3 image has s_first = 0 in journal superblock, and the 0 is passed to journal->j_head in journal_reset(), then to blocknr in cleanup_journal_tail(), in the end the J_ASSERT failed. So validate s_first after reading journal superblock from disk in journal_get_superblock() to ensure s_first is valid. The following script could reproduce it: fstype=ext3 blocksize=1024 img=$fstype.img offset=0 found=0 magic="c0 3b 39 98" dd if=/dev/zero of=$img bs=1M count=8 mkfs -t $fstype -b $blocksize -F $img filesize=`stat -c %s $img` while [ $offset -lt $filesize ] do if od -j $offset -N 4 -t x1 $img | grep -i "$magic";then echo "Found journal: $offset" found=1 break fi offset=`echo "$offset+$blocksize" | bc` done if [ $found -ne 1 ];then echo "Magic \"$magic\" not found" exit 1 fi dd if=/dev/zero of=$img seek=$(($offset+23)) conv=notrunc bs=1 count=1 mkdir -p ./mnt mount -o loop $img ./mnt Cc: Jan Kara <jack@suse.cz> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Eryu Guan <guaneryu@gmail.com> --- fs/jbd/journal.c | 8 ++++++++ fs/jbd2/journal.c | 8 ++++++++ 2 files changed, 16 insertions(+), 0 deletions(-)