From 2c98da4e6a3e106c340972adedc6f79c4c1969f2 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Tue, 28 Dec 2021 12:33:15 -0500 Subject: [PATCH] reisze2fs: sanity check free block group counts when calculating minimum size If one or more block group descriptor's free blocks count is insane, it's possible this can lead to a infinite loop in the function calculate_minimum_resize_size(), which is called by resize2fs -P or resize2fs -M. Add some sanity checks to avoid this. In the case where the file system is corrupt, this will result in resize2fs -P reporting an incorrect value, but that's OK, since when we try to do an actual resize operation, resize2fs requires that the file system be freshly checked using e2fsck. https://github.com/tytso/e2fsprogs/issues/94 Fixes: ac94445fc01f ("resize2fs: make minimum size estimates more reliable for mounted fs") Signed-off-by: Theodore Ts'o --- resize/resize2fs.c | 13 +++++++++-- tests/r_corrupt_fs/expect | 4 ++++ tests/r_corrupt_fs/name | 1 + tests/r_corrupt_fs/script | 45 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 61 insertions(+), 2 deletions(-) create mode 100644 tests/r_corrupt_fs/expect create mode 100644 tests/r_corrupt_fs/name create mode 100644 tests/r_corrupt_fs/script diff --git a/resize/resize2fs.c b/resize/resize2fs.c index 8a3d08db..26050fec 100644 --- a/resize/resize2fs.c +++ b/resize/resize2fs.c @@ -2928,8 +2928,17 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags) /* calculate how many blocks are needed for data */ data_needed = ext2fs_blocks_count(fs->super); for (grp = 0; grp < fs->group_desc_count; grp++) { - data_needed -= calc_group_overhead(fs, grp, old_desc_blocks); - data_needed -= ext2fs_bg_free_blocks_count(fs, grp); + __u32 n = ext2fs_bg_free_blocks_count(fs, grp); + + if (n > EXT2_BLOCKS_PER_GROUP(fs->super)) + n = EXT2_BLOCKS_PER_GROUP(fs->super); + n += calc_group_overhead(fs, grp, old_desc_blocks); + if (data_needed < n) { + if (flags & RESIZE_DEBUG_MIN_CALC) + printf("file system appears inconsistent?!?\n"); + return ext2fs_blocks_count(fs->super); + } + data_needed -= n; } #ifdef RESIZE2FS_DEBUG if (flags & RESIZE_DEBUG_MIN_CALC) diff --git a/tests/r_corrupt_fs/expect b/tests/r_corrupt_fs/expect new file mode 100644 index 00000000..fe0f2bc4 --- /dev/null +++ b/tests/r_corrupt_fs/expect @@ -0,0 +1,4 @@ +mke2fs -q -F -t ext4 -o Linux -b 1024 test.img 32M +debugfs -w -R "set_bg 1 free_blocks_count 65536" /tmp/foo.img +resize2fs -P /tmp/foo.img +Estimated minimum size of the filesystem: 6604 diff --git a/tests/r_corrupt_fs/name b/tests/r_corrupt_fs/name new file mode 100644 index 00000000..ed627419 --- /dev/null +++ b/tests/r_corrupt_fs/name @@ -0,0 +1 @@ +resize2fs -P of a corrupted file system diff --git a/tests/r_corrupt_fs/script b/tests/r_corrupt_fs/script new file mode 100644 index 00000000..08af91ed --- /dev/null +++ b/tests/r_corrupt_fs/script @@ -0,0 +1,45 @@ +if ! test -x $RESIZE2FS_EXE -o ! -x $DEBUGFS_EXE; then + echo "$test_name: $test_description: skipped (no debugfs/resize2fs)" + return 0 +fi + +OUT=$test_name.log +if [ -f $test_dir/expect.gz ]; then + EXP=$test_name.tmp + gunzip < $test_dir/expect.gz > $EXP1 +else + EXP=$test_dir/expect +fi + +echo mke2fs -q -F -t ext4 -o Linux -b 1024 test.img 32M > $OUT.new +$MKE2FS -q -F -t ext4 -o Linux -b 1024 $TMPFILE 32M >> $OUT.new 2>&1 + +echo debugfs -w -R \"set_bg 1 free_blocks_count 65536\" /tmp/foo.img >> $OUT.new +$DEBUGFS -w -R "set_bg 1 free_blocks_count 65536" $TMPFILE > /dev/null 2>&1 + +if type timeout > /dev/null 2>&1 ; then + TIMEOUT="timeout -v 30s" +else + TIMEOUT= +fi + +echo resize2fs -P /tmp/foo.img >> $OUT.new +$TIMEOUT $RESIZE2FS -P $TMPFILE >> $OUT.new 2>&1 + +sed -f $cmd_dir/filter.sed < $OUT.new > $OUT + +rm -f $TMPFILE $OUT.new + +cmp -s $OUT $EXP +status=$? + +if [ "$status" = 0 ] ; then + echo "$test_name: $test_description: ok" + touch $test_name.ok +else + echo "$test_name: $test_description: failed" + diff $DIFF_OPTS $EXP $OUT > $test_name.failed + rm -f $test_name.tmp +fi + +unset IMAGE OUT EXP TIMEOUT -- 2.34.1