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From f7da56758e5d15416339d640f79d6eee875d22a9 Mon Sep 17 00:00:00 2001
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From: Jan Kara <jack@suse.cz>
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Date: Tue, 25 Oct 2016 14:08:59 -0400
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Subject: [PATCH 09/16] mke2fs: Avoid crashes / infinite loops for absurdly
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large devices
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commit 101ef2e93c253ae62320628e8958067d2d2a4e2a
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When a device reports absurdly high size, some arithmetics in mke2fs can
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overflow (e.g. number of block descriptors) and we end in an infinite
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loop. Fix that by checking and refusing insanely large devices.
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Signed-off-by: Jan Kara <jack@suse.cz>
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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---
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misc/mke2fs.c | 12 ++++++++++++
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1 file changed, 12 insertions(+)
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diff --git a/misc/mke2fs.c b/misc/mke2fs.c
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index 2787a127..7cea0330 100644
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--- a/misc/mke2fs.c
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+++ b/misc/mke2fs.c
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@@ -1858,6 +1858,18 @@ profile_error:
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EXT2_BLOCK_SIZE(&fs_param));
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exit(1);
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}
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+ /*
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+ * Guard against group descriptor count overflowing... Mostly to avoid
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+ * strange results for absurdly large devices.
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+ */
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+ if (fs_blocks_count > ((1ULL << (fs_param.s_log_block_size + 3 + 32)) - 1)) {
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+ fprintf(stderr, _("%s: Size of device (0x%llx blocks) %s "
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+ "too big to create\n\t"
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+ "a filesystem using a blocksize of %d.\n"),
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+ program_name, fs_blocks_count, device_name,
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+ EXT2_BLOCK_SIZE(&fs_param));
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+ exit(1);
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+ }
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ext2fs_blocks_count_set(&fs_param, fs_blocks_count);
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--
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2.20.1
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