The patch titled
fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops
has been added to the -mm tree. Its filename is
fs-partitions-efic-corrupted-guid-partition-tables-can-cause-kernel-oops.patch
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------------------------------------------------------
Subject: fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops
From: Timo Warns <Warns@xxxxxxxxxxxx>
The kernel automatically evaluates partition tables of storage devices.
The code for evaluating GUID partitions (in fs/partitions/efi.c) contains
a bug that causes a kernel oops on certain corrupted GUID partition
tables.
This bug has security impacts, because it allows, for example, to
prepare a storage device that crashes a kernel subsystem upon connecting
the device (e.g., a "USB Stick of (Partial) Death").
crc = efi_crc32((const unsigned char *) (*gpt), le32_to_cpu((*gpt)->header_size));
computes a CRC32 checksum over gpt covering (*gpt)->header_size bytes.
There is no validation of (*gpt)->header_size before the efi_crc32 call.
A corrupted partition table may have large values for (*gpt)->header_size.
In this case, the CRC32 computation access memory beyond the memory
allocated for gpt, which may cause a kernel heap overflow.
Validate value of GUID partition table header size.
Signed-off-by: Timo Warns <warns@xxxxxxxxxxxx>
Cc: Matt Domsch <Matt_Domsch@xxxxxxxx>
Cc: Eugene Teo <eugeneteo@xxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/partitions/efi.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN fs/partitions/efi.c~fs-partitions-efic-corrupted-guid-partition-tables-can-cause-kernel-oops fs/partitions/efi.c
--- a/fs/partitions/efi.c~fs-partitions-efic-corrupted-guid-partition-tables-can-cause-kernel-oops
+++ a/fs/partitions/efi.c
@@ -310,6 +310,15 @@ static int is_gpt_valid(struct parsed_pa
goto fail;
}
+ /* Check the GUID Partition Table header size */
+ if (le32_to_cpu((*gpt)->header_size) > bdev_logical_block_size(state->bdev)) {
+ pr_debug("GUID Partition Table Header size is wrong:"
+ "%u > %u\n",
+ le32_to_cpu((*gpt)->header_size),
+ bdev_logical_block_size(state->bdev));
+ goto fail;
+ }
+
/* Check the GUID Partition Table CRC */
origcrc = le32_to_cpu((*gpt)->header_crc32);
(*gpt)->header_crc32 = 0;
_
Patches currently in -mm which might be from Warns@xxxxxxxxxxxx are
fs-partitions-ldmc-fix-oops-caused-by-corrupted-partition-table.patch
fs-partitions-ldmc-fix-oops-caused-by-corrupted-partition-table-checkpatch-fixes.patch
fs-partitions-efic-corrupted-guid-partition-tables-can-cause-kernel-oops.patch
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