Patchwork partitions/efi: Fix partition name parsing in GUID partition entry

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Submitter Nikolai Merinov
Date Nov. 24, 2018, 4:21 p.m.
Message ID <20181124162123.21300-1-n.merinov@inango-systems.com>
Download mbox | patch
Permalink /patch/664179/
State New
Headers show

Comments

Nikolai Merinov - Nov. 24, 2018, 4:21 p.m.
GUID partition entry defined to have a partition name as 36 UTF-16LE
code units. This means that on big-endian platforms ASCII symbols
would be read with 0xXX00 efi_char16_t character code. In order to
correctly extract ASCII characters from a partition name field we
should be converted from 16LE to CPU architecture.

The problem exists on all big endian platforms.

Signed-off-by: Nikolai Merinov <n.merinov@inango-systems.com>
---
 block/partitions/efi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
kbuild test robot - Nov. 25, 2018, 9:16 p.m.
Hi Nikolai,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on block/for-next]
[also build test WARNING on v4.20-rc3 next-20181123]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Nikolai-Merinov/partitions-efi-Fix-partition-name-parsing-in-GUID-partition-entry/20181125-060728
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: x86_64-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   include/linux/slab.h:332:43: warning: dubious: x & !y
   include/linux/slab.h:332:43: warning: dubious: x & !y
   include/linux/slab.h:332:43: warning: dubious: x & !y
>> block/partitions/efi.c:732:32: warning: cast to restricted __le16

vim +732 block/partitions/efi.c

   672	
   673	/**
   674	 * efi_partition(struct parsed_partitions *state)
   675	 * @state: disk parsed partitions
   676	 *
   677	 * Description: called from check.c, if the disk contains GPT
   678	 * partitions, sets up partition entries in the kernel.
   679	 *
   680	 * If the first block on the disk is a legacy MBR,
   681	 * it will get handled by msdos_partition().
   682	 * If it's a Protective MBR, we'll handle it here.
   683	 *
   684	 * We do not create a Linux partition for GPT, but
   685	 * only for the actual data partitions.
   686	 * Returns:
   687	 * -1 if unable to read the partition table
   688	 *  0 if this isn't our partition table
   689	 *  1 if successful
   690	 *
   691	 */
   692	int efi_partition(struct parsed_partitions *state)
   693	{
   694		gpt_header *gpt = NULL;
   695		gpt_entry *ptes = NULL;
   696		u32 i;
   697		unsigned ssz = bdev_logical_block_size(state->bdev) / 512;
   698	
   699		if (!find_valid_gpt(state, &gpt, &ptes) || !gpt || !ptes) {
   700			kfree(gpt);
   701			kfree(ptes);
   702			return 0;
   703		}
   704	
   705		pr_debug("GUID Partition Table is valid!  Yea!\n");
   706	
   707		for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
   708			struct partition_meta_info *info;
   709			unsigned label_count = 0;
   710			unsigned label_max;
   711			u64 start = le64_to_cpu(ptes[i].starting_lba);
   712			u64 size = le64_to_cpu(ptes[i].ending_lba) -
   713				   le64_to_cpu(ptes[i].starting_lba) + 1ULL;
   714	
   715			if (!is_pte_valid(&ptes[i], last_lba(state->bdev)))
   716				continue;
   717	
   718			put_partition(state, i+1, start * ssz, size * ssz);
   719	
   720			/* If this is a RAID volume, tell md */
   721			if (!efi_guidcmp(ptes[i].partition_type_guid, PARTITION_LINUX_RAID_GUID))
   722				state->parts[i + 1].flags = ADDPART_FLAG_RAID;
   723	
   724			info = &state->parts[i + 1].info;
   725			efi_guid_to_str(&ptes[i].unique_partition_guid, info->uuid);
   726	
   727			/* Naively convert UTF16-LE to 7 bits. */
   728			label_max = min(ARRAY_SIZE(info->volname) - 1,
   729					ARRAY_SIZE(ptes[i].partition_name));
   730			info->volname[label_max] = 0;
   731			while (label_count < label_max) {
 > 732				u8 c = le16_to_cpu(ptes[i].partition_name[label_count]) & 0xff;

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Patch

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 39f70d968754..ea50ee1505ed 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -729,7 +729,7 @@  int efi_partition(struct parsed_partitions *state)
 				ARRAY_SIZE(ptes[i].partition_name));
 		info->volname[label_max] = 0;
 		while (label_count < label_max) {
-			u8 c = ptes[i].partition_name[label_count] & 0xff;
+			u8 c = le16_to_cpu(ptes[i].partition_name[label_count]) & 0xff;
 			if (c && !isprint(c))
 				c = '!';
 			info->volname[label_count] = c;