From: Wang YanQing <udknight@gmail.com>
Date: Thu, 10 May 2018 11:06:37 +0800
Subject: [PATCH] block: add verifier for cmdline partition
Git-commit: 645d40952c5a6cf916f9dc566cf07ae5348f64c7
Patch-mainline: v4.18-rc1
References: bsc#1104967,FATE#325924

I meet strange filesystem corruption issue recently, the reason
is there are overlaps partitions in cmdline partition argument.

This patch add verifier for cmdline partition, then if there are
overlaps partitions, cmdline_partition will log a warning. We don't
treat overlaps partition as a error:
"
Caizhiyong <caizhiyong@hisilicon.com> said:
Partition overlap was intentionally designed in this cmdline partition.
reference http://lists.infradead.org/pipermail/linux-mtd/2013-August/048092.html
"

Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 block/partitions/cmdline.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/block/partitions/cmdline.c b/block/partitions/cmdline.c
index e333583ab38c..60fb3df9897c 100644
--- a/block/partitions/cmdline.c
+++ b/block/partitions/cmdline.c
@@ -58,6 +58,62 @@ static int __init cmdline_parts_setup(char *s)
 }
 __setup("blkdevparts=", cmdline_parts_setup);
 
+static bool has_overlaps(sector_t from, sector_t size,
+			 sector_t from2, sector_t size2)
+{
+	sector_t end = from + size;
+	sector_t end2 = from2 + size2;
+
+	if (from >= from2 && from < end2)
+		return true;
+
+	if (end > from2 && end <= end2)
+		return true;
+
+	if (from2 >= from && from2 < end)
+		return true;
+
+	if (end2 > from && end2 <= end)
+		return true;
+
+	return false;
+}
+
+static inline void overlaps_warns_header(void)
+{
+	pr_warn("Overlapping partitions are used in command line partitions.");
+	pr_warn("Don't use filesystems on overlapping partitions:");
+}
+
+static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
+{
+	int i;
+	bool header = true;
+
+	for (; slot < state->limit && state->parts[slot].has_info; slot++) {
+		for (i = slot+1; i < state->limit && state->parts[i].has_info;
+		     i++) {
+			if (has_overlaps(state->parts[slot].from,
+					 state->parts[slot].size,
+					 state->parts[i].from,
+					 state->parts[i].size)) {
+				if (header) {
+					header = false;
+					overlaps_warns_header();
+				}
+				pr_warn("%s[%llu,%llu] overlaps with "
+					"%s[%llu,%llu].",
+					state->parts[slot].info.volname,
+					(u64)state->parts[slot].from << 9,
+					(u64)state->parts[slot].size << 9,
+					state->parts[i].info.volname,
+					(u64)state->parts[i].from << 9,
+					(u64)state->parts[i].size << 9);
+			}
+		}
+	}
+}
+
 /*
  * Purpose: allocate cmdline partitions.
  * Returns:
@@ -93,6 +149,7 @@ int cmdline_partition(struct parsed_partitions *state)
 	disk_size = get_capacity(state->bdev->bd_disk) << 9;
 
 	cmdline_parts_set(parts, disk_size, 1, add_part, (void *)state);
+	cmdline_parts_verifier(1, state);
 
 	strlcat(state->pp_buf, "\n", PAGE_SIZE);
 
-- 
2.16.4