5.4-stable review patch. If anyone has any objections, please let me know.
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From: Jann Horn jannh@google.com
commit 80e648042e512d5a767da251d44132553fe04ae0 upstream.
Fix several issues in partition probing:
- The bailout for a bad partoffset must use put_dev_sector(), since the preceding read_part_sector() succeeded. - If the partition table claims a silly sector size like 0xfff bytes (which results in partition table entries straddling sector boundaries), bail out instead of accessing out-of-bounds memory. - We must not assume that the partition table contains proper NUL termination - use strnlen() and strncmp() instead of strlen() and strcmp().
Cc: stable@vger.kernel.org Signed-off-by: Jann Horn jannh@google.com Link: https://lore.kernel.org/r/20250214-partition-mac-v1-1-c1c626dffbd5@google.co... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/partitions/mac.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
--- a/block/partitions/mac.c +++ b/block/partitions/mac.c @@ -51,13 +51,25 @@ int mac_partition(struct parsed_partitio } secsize = be16_to_cpu(md->block_size); put_dev_sector(sect); + + /* + * If the "block size" is not a power of 2, things get weird - we might + * end up with a partition straddling a sector boundary, so we wouldn't + * be able to read a partition entry with read_part_sector(). + * Real block sizes are probably (?) powers of two, so just require + * that. + */ + if (!is_power_of_2(secsize)) + return -1; datasize = round_down(secsize, 512); data = read_part_sector(state, datasize / 512, §); if (!data) return -1; partoffset = secsize % 512; - if (partoffset + sizeof(*part) > datasize) + if (partoffset + sizeof(*part) > datasize) { + put_dev_sector(sect); return -1; + } part = (struct mac_partition *) (data + partoffset); if (be16_to_cpu(part->signature) != MAC_PARTITION_MAGIC) { put_dev_sector(sect); @@ -110,8 +122,8 @@ int mac_partition(struct parsed_partitio int i, l;
goodness++; - l = strlen(part->name); - if (strcmp(part->name, "/") == 0) + l = strnlen(part->name, sizeof(part->name)); + if (strncmp(part->name, "/", sizeof(part->name)) == 0) goodness++; for (i = 0; i <= l - 4; ++i) { if (strncasecmp(part->name + i, "root",