55 lines
2.0 KiB
Plaintext
55 lines
2.0 KiB
Plaintext
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From: Timo Warns <Warns@pre-sense.de>
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Subject: fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops
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References: bnc#687113 CVE-2011-1577
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Patch-mainline: Probably 2.6.39; In -mm already
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The kernel automatically evaluates partition tables of storage devices.
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The code for evaluating GUID partitions (in fs/partitions/efi.c) contains
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a bug that causes a kernel oops on certain corrupted GUID partition
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tables.
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This bug has security impacts, because it allows, for example, to
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prepare a storage device that crashes a kernel subsystem upon connecting
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the device (e.g., a "USB Stick of (Partial) Death").
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crc = efi_crc32((const unsigned char *) (*gpt), le32_to_cpu((*gpt)->header_size));
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computes a CRC32 checksum over gpt covering (*gpt)->header_size bytes.
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There is no validation of (*gpt)->header_size before the efi_crc32 call.
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A corrupted partition table may have large values for (*gpt)->header_size.
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In this case, the CRC32 computation access memory beyond the memory
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allocated for gpt, which may cause a kernel heap overflow.
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Validate value of GUID partition table header size.
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Signed-off-by: Timo Warns <warns@pre-sense.de>
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Cc: Matt Domsch <Matt_Domsch@dell.com>
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Cc: Eugene Teo <eugeneteo@kernel.sg>
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Cc: Dave Jones <davej@codemonkey.org.uk>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Acked-by: Jeff Mahoney <jeffm@suse.com>
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---
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fs/partitions/efi.c | 9 +++++++++
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1 file changed, 9 insertions(+)
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--- a/fs/partitions/efi.c
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+++ b/fs/partitions/efi.c
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@@ -310,6 +310,15 @@ static int is_gpt_valid(struct parsed_pa
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goto fail;
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}
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+ /* Check the GUID Partition Table header size */
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+ if (le32_to_cpu((*gpt)->header_size) >
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+ bdev_logical_block_size(state->bdev)) {
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+ pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
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+ le32_to_cpu((*gpt)->header_size),
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+ bdev_logical_block_size(state->bdev));
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+ goto fail;
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+ }
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+
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/* Check the GUID Partition Table CRC */
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origcrc = le32_to_cpu((*gpt)->header_crc32);
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(*gpt)->header_crc32 = 0;
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