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From 21e41eeef968941c1ee0126852fdb705967730ea Mon Sep 17 00:00:00 2001
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From: Theodore Ts'o <tytso@mit.edu>
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Date: Fri, 8 Nov 2019 11:58:10 -0500
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Subject: [PATCH 05/10] libext2fs: verify the block numbers for the allocation
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bitmaps are valid
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This avoids a potential UBsan failure when we multiply an insanely
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high block number with the block size and we get a multiplication
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overflow.
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Google-Bug-Id: 128130353
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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---
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lib/ext2fs/rw_bitmaps.c | 14 ++++++++------
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1 file changed, 8 insertions(+), 6 deletions(-)
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diff --git a/lib/ext2fs/rw_bitmaps.c b/lib/ext2fs/rw_bitmaps.c
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index e092cab0..d80c9eb8 100644
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--- a/lib/ext2fs/rw_bitmaps.c
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+++ b/lib/ext2fs/rw_bitmaps.c
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@@ -306,9 +306,10 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
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for (i = 0; i < fs->group_desc_count; i++) {
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if (block_bitmap) {
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blk = ext2fs_block_bitmap_loc(fs, i);
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- if (csum_flag &&
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- ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT) &&
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- ext2fs_group_desc_csum_verify(fs, i))
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+ if ((csum_flag &&
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+ ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT) &&
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+ ext2fs_group_desc_csum_verify(fs, i)) ||
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+ (blk >= ext2fs_blocks_count(fs->super)))
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blk = 0;
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if (blk) {
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retval = io_channel_read_blk64(fs->io, blk,
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@@ -340,9 +341,10 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
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}
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if (inode_bitmap) {
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blk = ext2fs_inode_bitmap_loc(fs, i);
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- if (csum_flag &&
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- ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT) &&
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- ext2fs_group_desc_csum_verify(fs, i))
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+ if ((csum_flag &&
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+ ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT) &&
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+ ext2fs_group_desc_csum_verify(fs, i)) ||
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+ (blk >= ext2fs_blocks_count(fs->super)))
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blk = 0;
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if (blk) {
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retval = io_channel_read_blk64(fs->io, blk,
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--
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2.21.1
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