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Commit 3eb8e74ec72736b9b9d728bad30484ec89c91dde

Authored by Timo Warns
Committed by Linus Torvalds
1 parent 658c74cf3c
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops 

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.

[akpm@linux-foundation.org: fix layout and indenting]
Signed-off-by: Timo Warns <warns@pre-sense.de>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Cc: Eugene Teo <eugeneteo@kernel.sg>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 9 additions and 0 deletions Side-by-side Diff

... ... @@ -310,6 +310,15 @@
310 310 goto fail;
311 311 }
312 312  
  313 + /* Check the GUID Partition Table header size */
  314 + if (le32_to_cpu((*gpt)->header_size) >
  315 + bdev_logical_block_size(state->bdev)) {
  316 + pr_debug("GUID Partition Table Header size is wrong: %u > %u\n",
  317 + le32_to_cpu((*gpt)->header_size),
  318 + bdev_logical_block_size(state->bdev));
  319 + goto fail;
  320 + }
  321 +
313 322 /* Check the GUID Partition Table CRC */
314 323 origcrc = le32_to_cpu((*gpt)->header_crc32);
315 324 (*gpt)->header_crc32 = 0;