Re: [PATCH] md/bitmap: Fix bitmap chunk size overflow issues.

Dear Jack, dear Florian-Ewald,

Thank you for the patch.

Am 14.10.22 um 14:20 schrieb Jack Wang:

From: Florian-Ewald Mueller florian-ewald.mueller@ionos.com

• limit bitmap chunk size internal u64 variable to values not overflowing the u32 bitmap superblock structure variable stored on persistent media.
• assign bitmap chunk size internal u64 variable from unsigned values to avoid possible sign extension artifacts when assigning from a s32 value.

The bug has been there since at least kernel 4.0.

Did you find this during code review or hit actual problems? If so, a reproducer would be nice to have. (A small nit, should you resend, if you removed the dot/period from the end of the commit message summary/title, that’d be great.)

Kind regards,

Paul

Cc: stable@vger.kernel.org

Signed-off-by: Florian-Ewald Mueller florian-ewald.mueller@ionos.com Signed-off-by: Jack Wang jinpu.wang@ionos.com

---

drivers/md/md-bitmap.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index bf6dffadbe6f..b266711485a8 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -486,7 +486,7 @@ void md_bitmap_print_sb(struct bitmap *bitmap) sb = kmap_atomic(bitmap->storage.sb_page); pr_debug("%s: bitmap file superblock:\n", bmname(bitmap)); pr_debug(" magic: %08x\n", le32_to_cpu(sb->magic));

• pr_debug(" version: %d\n", le32_to_cpu(sb->version));

• pr_debug(" version: %u\n", le32_to_cpu(sb->version)); pr_debug(" uuid: %08x.%08x.%08x.%08x\n", le32_to_cpu(*(__le32 *)(sb->uuid+0)), le32_to_cpu(*(__le32 *)(sb->uuid+4)),

@@ -497,11 +497,11 @@ void md_bitmap_print_sb(struct bitmap *bitmap) pr_debug("events cleared: %llu\n", (unsigned long long) le64_to_cpu(sb->events_cleared)); pr_debug(" state: %08x\n", le32_to_cpu(sb->state));

• pr_debug(" chunksize: %d B\n", le32_to_cpu(sb->chunksize));
• pr_debug(" daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));

• pr_debug(" chunksize: %u B\n", le32_to_cpu(sb->chunksize));
• pr_debug(" daemon sleep: %us\n", le32_to_cpu(sb->daemon_sleep)); pr_debug(" sync size: %llu KB\n", (unsigned long long)le64_to_cpu(sb->sync_size)/2);

• pr_debug("max write behind: %d\n", le32_to_cpu(sb->write_behind));

• pr_debug("max write behind: %u\n", le32_to_cpu(sb->write_behind)); kunmap_atomic(sb); }

@@ -2105,7 +2105,8 @@ int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks, bytes = DIV_ROUND_UP(chunks, 8); if (!bitmap->mddev->bitmap_info.external) bytes += sizeof(bitmap_super_t);

• } while (bytes > (space << 9));
  

• } while (bytes > (space << 9) && (chunkshift + BITMAP_BLOCK_SHIFT) <
  

• 	(BITS_PER_BYTE * sizeof(((bitmap_super_t *)0)->chunksize) - 1));
  

  } else chunkshift = ffz(~chunksize) - BITMAP_BLOCK_SHIFT;

@@ -2150,7 +2151,7 @@ int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks, bitmap->counts.missing_pages = pages; bitmap->counts.chunkshift = chunkshift; bitmap->counts.chunks = chunks;

• bitmap->mddev->bitmap_info.chunksize = 1 << (chunkshift +

• bitmap->mddev->bitmap_info.chunksize = 1UL << (chunkshift + BITMAP_BLOCK_SHIFT);

blocks = min(old_counts.chunks << old_counts.chunkshift, @@ -2176,8 +2177,8 @@ int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks, bitmap->counts.missing_pages = old_counts.pages; bitmap->counts.chunkshift = old_counts.chunkshift; bitmap->counts.chunks = old_counts.chunks;

• 		bitmap->mddev->bitmap_info.chunksize = 1 << (old_counts.chunkshift +
  

• 							     BITMAP_BLOCK_SHIFT);
  

• 		bitmap->mddev->bitmap_info.chunksize =
  

• 			1UL << (old_counts.chunkshift + BITMAP_BLOCK_SHIFT);
  	blocks = old_counts.chunks << old_counts.chunkshift;
  	pr_warn("Could not pre-allocate in-memory bitmap for cluster raid\n");
  	break;
  

@@ -2534,6 +2535,9 @@ chunksize_store(struct mddev *mddev, const char *buf, size_t len) if (csize < 512 || !is_power_of_2(csize)) return -EINVAL;

• if (csize >= (1UL << (BITS_PER_BYTE *

• sizeof(((bitmap_super_t *)0)->chunksize))))
  

• return -EOVERFLOW;
  

  mddev->bitmap_info.chunksize = csize; return len; }