From 05c69d298c96703741cac9a5cbbf6c53bd55a6e2 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 15 May 2012 08:22:04 +0200 Subject: block: fix buffer overflow when printing partition UUIDs 6d1d8050b4bc8 "block, partition: add partition_meta_info to hd_struct" added part_unpack_uuid() which assumes that the passed in buffer has enough space for sprintfing "%pU" - 37 characters including '\0'. Unfortunately, b5af921ec0233 "init: add support for root devices specified by partition UUID" supplied 33 bytes buffer to the function leading to the following panic with stackprotector enabled. Kernel panic - not syncing: stack-protector: Kernel stack corrupted in: ffffffff81b14c7e [] panic+0xba/0x1c6 [] ? printk_all_partitions+0x259/0x26xb [] __stack_chk_fail+0x1b/0x20 [] printk_all_paritions+0x259/0x26xb [] mount_block_root+0x1bc/0x27f [] mount_root+0x57/0x5b [] prepare_namespace+0x13d/0x176 [] ? release_tgcred.isra.4+0x330/0x30 [] kernel_init+0x155/0x15a [] ? schedule_tail+0x27/0xb0 [] kernel_thread_helper+0x5/0x10 [] ? start_kernel+0x3c5/0x3c5 [] ? gs_change+0x13/0x13 Increase the buffer size, remove the dangerous part_unpack_uuid() and use snprintf() directly from printk_all_partitions(). Signed-off-by: Tejun Heo Reported-by: Szymon Gruszczynski Cc: Will Drewry Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe diff --git a/block/genhd.c b/block/genhd.c index df9816e..9cf5583 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -743,7 +743,7 @@ void __init printk_all_partitions(void) struct hd_struct *part; char name_buf[BDEVNAME_SIZE]; char devt_buf[BDEVT_SIZE]; - u8 uuid[PARTITION_META_INFO_UUIDLTH * 2 + 1]; + char uuid_buf[PARTITION_META_INFO_UUIDLTH * 2 + 5]; /* * Don't show empty devices or things that have been @@ -762,14 +762,16 @@ void __init printk_all_partitions(void) while ((part = disk_part_iter_next(&piter))) { bool is_part0 = part == &disk->part0; - uuid[0] = 0; + uuid_buf[0] = '\0'; if (part->info) - part_unpack_uuid(part->info->uuid, uuid); + snprintf(uuid_buf, sizeof(uuid_buf), "%pU", + part->info->uuid); printk("%s%s %10llu %s %s", is_part0 ? "" : " ", bdevt_str(part_devt(part), devt_buf), (unsigned long long)part->nr_sects >> 1, - disk_name(disk, part->partno, name_buf), uuid); + disk_name(disk, part->partno, name_buf), + uuid_buf); if (is_part0) { if (disk->driverfs_dev != NULL && disk->driverfs_dev->driver != NULL) diff --git a/include/linux/genhd.h b/include/linux/genhd.h index e61d319..017a7fb 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -222,12 +222,6 @@ static inline void part_pack_uuid(const u8 *uuid_str, u8 *to) } } -static inline char *part_unpack_uuid(const u8 *uuid, char *out) -{ - sprintf(out, "%pU", uuid); - return out; -} - static inline int disk_max_parts(struct gendisk *disk) { if (disk->flags & GENHD_FL_EXT_DEVT) -- cgit v0.10.2