From: Jann Horn <jannh@xxxxxxxxxx> 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@xxxxxxxxxxxxxxx Signed-off-by: Jann Horn <jannh@xxxxxxxxxx> Link: https://lore.kernel.org/r/20250214-partition-mac-v1-1-c1c626dffbd5@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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", Patches currently in stable-queue which might be from jannh@xxxxxxxxxx are queue-5.4/usb-cdc-acm-fix-handling-of-oversized-fragments.patch queue-5.4/partitions-mac-fix-handling-of-bogus-partition-table.patch queue-5.4/usb-cdc-acm-check-control-transfer-buffer-size-before-access.patch
