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

Lukáš Czerner
2013-10-07T14:30:48Z

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.

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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