Re: [PATCH 14/31] libext2fs: Fix ext2fs_open2() truncation of the superblock parameter

Darrick J. Wong
2013-10-07T18:42:59Z

On Mon, Oct 07, 2013 at 04:30:39PM +0200, Lukáš Czerner wrote:
> On Mon, 30 Sep 2013, Darrick J. Wong wrote:
>
> > Date: Mon, 30 Sep 2013 18:28:12 -0700
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > To: tytso@mit.edu, darrick.wong@oracle.com
> > Cc: linux-ext4@vger.kernel.org
> > Subject: [PATCH 14/31] libext2fs: Fix ext2fs_open2() truncation of the
> > superblock parameter
> >
> > Since it's possible for very large filesystems to store backup superblocks at
> > very large (> 2^32) block numbers, we need to be able to handle the case of a
> > caller directing us to read one of these high-numbered backups.
>
> I do not think this is enough, because in ext2fs_open2() or rather
> ext2fs_open3() as you rename it we read the superblock block with
> io_channel_read_blk() which takes unsigned long as a block number
> rather than io_channel_read_blk64().
>
> Having a simple test for this particular case might be useful.

Good catch! I've updated the patch.

--D
>
> Thanks!
> -Lukas
>
>
>
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> > debugfs/debugfs.c | 4 ++--
> > e2fsck/journal.c | 6 +++---
> > e2fsck/unix.c | 8 ++++----
> > lib/ext2fs/ext2fs.h | 4 ++++
> > lib/ext2fs/openfs.c | 13 +++++++++++--
> > misc/dumpe2fs.c | 4 ++--
> > 6 files changed, 26 insertions(+), 13 deletions(-)
> >
> >
> > diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
> > index 2660218..da44ce4 100644
> > --- a/debugfs/debugfs.c
> > +++ b/debugfs/debugfs.c
> > @@ -80,8 +80,8 @@ static void open_filesystem(char *device, int open_flags, blk64_t superblock,
> > if (catastrophic)
> > open_flags |= EXT2_FLAG_SKIP_MMP;
> >
> > - retval = ext2fs_open(device, open_flags, superblock, blocksize,
> > - unix_io_manager, &current_fs);
> > + retval = ext2fs_open3(device, NULL, open_flags, superblock, blocksize,
> > + unix_io_manager, &current_fs);
> > if (retval) {
> > com_err(device, retval, "while opening filesystem");
> > current_fs = NULL;
> > diff --git a/e2fsck/journal.c b/e2fsck/journal.c
> > index 2509303..af35a38 100644
> > --- a/e2fsck/journal.c
> > +++ b/e2fsck/journal.c
> > @@ -967,9 +967,9 @@ int e2fsck_run_ext3_journal(e2fsck_t ctx)
> >
> > ext2fs_mmp_stop(ctx->fs);
> > ext2fs_free(ctx->fs);
> > - retval = ext2fs_open(ctx->filesystem_name, EXT2_FLAG_RW,
> > - ctx->superblock, blocksize, io_ptr,
> > - &ctx->fs);
> > + retval = ext2fs_open3(ctx->filesystem_name, NULL, EXT2_FLAG_RW,
> > + ctx->superblock, blocksize, io_ptr,
> > + &ctx->fs);
> > if (retval) {
> > com_err(ctx->program_name, retval,
> > _("while trying to re-open %s"),
> > diff --git a/e2fsck/unix.c b/e2fsck/unix.c
> > index 0546653..fb41ca0 100644
> > --- a/e2fsck/unix.c
> > +++ b/e2fsck/unix.c
> > @@ -1040,7 +1040,7 @@ static errcode_t try_open_fs(e2fsck_t ctx, int flags, io_manager io_ptr,
> >
> > *ret_fs = NULL;
> > if (ctx->superblock && ctx->blocksize) {
> > - retval = ext2fs_open2(ctx->filesystem_name, ctx->io_options,
> > + retval = ext2fs_open3(ctx->filesystem_name, ctx->io_options,
> > flags, ctx->superblock, ctx->blocksize,
> > io_ptr, ret_fs);
> > } else if (ctx->superblock) {
> > @@ -1051,7 +1051,7 @@ static errcode_t try_open_fs(e2fsck_t ctx, int flags, io_manager io_ptr,
> > ext2fs_free(*ret_fs);
> > *ret_fs = NULL;
> > }
> > - retval = ext2fs_open2(ctx->filesystem_name,
> > + retval = ext2fs_open3(ctx->filesystem_name,
> > ctx->io_options, flags,
> > ctx->superblock, blocksize,
> > io_ptr, ret_fs);
> > @@ -1059,7 +1059,7 @@ static errcode_t try_open_fs(e2fsck_t ctx, int flags, io_manager io_ptr,
> > break;
> > }
> > } else
> > - retval = ext2fs_open2(ctx->filesystem_name, ctx->io_options,
> > + retval = ext2fs_open3(ctx->filesystem_name, ctx->io_options,
> > flags, 0, 0, io_ptr, ret_fs);
> >
> > if (retval == 0)
> > @@ -1375,7 +1375,7 @@ failure:
> > * don't need to update the mount count and last checked
> > * fields in the backup superblock (the kernel doesn't update
> > * the backup superblocks anyway). With newer versions of the
> > - * library this flag is set by ext2fs_open2(), but we set this
> > + * library this flag is set by ext2fs_open3(), but we set this
> > * here just to be sure. (No, we don't support e2fsck running
> > * with some other libext2fs than the one that it was shipped
> > * with, but just in case....)
> > diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> > index c37e00b..d5d8d03 100644
> > --- a/lib/ext2fs/ext2fs.h
> > +++ b/lib/ext2fs/ext2fs.h
> > @@ -1437,6 +1437,10 @@ extern errcode_t ext2fs_open2(const char *name, const char *io_options,
> > int flags, int superblock,
> > unsigned int block_size, io_manager manager,
> > ext2_filsys *ret_fs);
> > +extern errcode_t ext2fs_open3(const char *name, const char *io_options,
> > + int flags, blk64_t superblock,
> > + unsigned int block_size, io_manager manager,
> > + ext2_filsys *ret_fs);
> > extern blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs,
> > blk64_t group_block, dgrp_t i);
> > extern blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block,
> > diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
> > index 89117f4..3c0bf14 100644
> > --- a/lib/ext2fs/openfs.c
> > +++ b/lib/ext2fs/openfs.c
> > @@ -76,6 +76,15 @@ errcode_t ext2fs_open(const char *name, int flags, int superblock,
> > manager, ret_fs);
> > }
> >
> > +errcode_t ext2fs_open2(const char *name, const char *io_options,
> > + int flags, int superblock,
> > + unsigned int block_size, io_manager manager,
> > + ext2_filsys *ret_fs)
> > +{
> > + return ext2fs_open3(name, io_options, flags, superblock, block_size,
> > + manager, ret_fs);
> > +}
> > +
> > /*
> > * Note: if superblock is non-zero, block-size must also be non-zero.
> > * Superblock and block_size can be zero to use the default size.
> > @@ -90,8 +99,8 @@ errcode_t ext2fs_open(const char *name, int flags, int superblock,
> > * EXT2_FLAG_64BITS - Allow 64-bit bitfields (needed for large
> > * filesystems)
> > */
> > -errcode_t ext2fs_open2(const char *name, const char *io_options,
> > - int flags, int superblock,
> > +errcode_t ext2fs_open3(const char *name, const char *io_options,
> > + int flags, blk64_t superblock,
> > unsigned int block_size, io_manager manager,
> > ext2_filsys *ret_fs)
> > {
> > diff --git a/misc/dumpe2fs.c b/misc/dumpe2fs.c
> > index ae70f70..b139977 100644
> > --- a/misc/dumpe2fs.c
> > +++ b/misc/dumpe2fs.c
> > @@ -611,7 +611,7 @@ int main (int argc, char ** argv)
> > for (use_blocksize = EXT2_MIN_BLOCK_SIZE;
> > use_blocksize <= EXT2_MAX_BLOCK_SIZE;
> > use_blocksize *= 2) {
> > - retval = ext2fs_open (device_name, flags,
> > + retval = ext2fs_open3(device_name, NULL, flags,
> > use_superblock,
> > use_blocksize, unix_io_manager,
> > &fs);
> > @@ -619,7 +619,7 @@ int main (int argc, char ** argv)
> > break;
> > }
> > } else
> > - retval = ext2fs_open (device_name, flags, use_superblock,
> > + retval = ext2fs_open3(device_name, NULL, flags, use_superblock,
> > use_blocksize, unix_io_manager, &fs);
> > if (retval) {
> > com_err (program_name, retval, _("while trying to open %s"),
> >
> > --
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