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From 742255d914bf06fa8e8a3f048aae2c738657af52 Mon Sep 17 00:00:00 2001
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From: Theodore Ts'o <tytso@mit.edu>
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Date: Fri, 2 Oct 2020 14:47:25 -0400
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Subject: [PATCH 11/46] resize2fs: prevent block group descriptors from
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overflowing the first bg
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Content-Type: text/plain
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For 1k block file systems, resizing a file system larger than
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1073610752 blocks will result in the size of the block group
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descriptors to be so large that it will overlap with the backup
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superblock in block group #1. This problem can be reproduced via:
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mke2fs -t ext4 /tmp/foo.img 200M
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resize2fs /tmp/foo.img 1T
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e2fsck -f /tmp/foo.img
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https://github.com/tytso/e2fsprogs/issues/50
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Signed-off-by: Lukas Czerner <lczerner@redhat.com>
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---
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resize/main.c | 14 ++++++++++++++
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1 file changed, 14 insertions(+)
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diff --git a/resize/main.c b/resize/main.c
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index a0c31c06..5e771d2a 100644
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--- a/resize/main.c
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+++ b/resize/main.c
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@@ -269,6 +269,8 @@ int main (int argc, char ** argv)
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long sysval;
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int len, mount_flags;
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char *mtpt, *undo_file = NULL;
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+ dgrp_t new_group_desc_count;
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+ unsigned long new_desc_blocks;
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#ifdef ENABLE_NLS
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setlocale(LC_MESSAGES, "");
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@@ -528,6 +530,18 @@ int main (int argc, char ** argv)
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exit(1);
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}
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}
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+ new_group_desc_count = ext2fs_div64_ceil(new_size -
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+ fs->super->s_first_data_block,
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+ EXT2_BLOCKS_PER_GROUP(fs->super));
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+ new_desc_blocks = ext2fs_div_ceil(new_group_desc_count,
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+ EXT2_DESC_PER_BLOCK(fs->super));
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+ if ((new_desc_blocks + fs->super->s_first_data_block) >
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+ EXT2_BLOCKS_PER_GROUP(fs->super)) {
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+ com_err(program_name, 0,
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+ _("New size results in too many block group "
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+ "descriptors.\n"));
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+ exit(1);
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+ }
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if (!force && new_size < min_size) {
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com_err(program_name, 0,
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--
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2.35.1
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