From ccece235d3737221e7a1118fdbd8474112adac84 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Tue, 10 Jul 2012 20:30:10 -0500 Subject: [PATCH] rbd: fixes in rbd_header_from_disk() This fixes a few issues in rbd_header_from_disk(): - There is a check intended to catch overflow, but it's wrong in two ways. - First, the type we don't want to overflow is size_t, not unsigned int, and there is now a SIZE_MAX we can use for use with that type. - Second, we're allocating the snapshot ids and snapshot image sizes separately (each has type u64; on disk they grouped together as a rbd_image_header_ondisk structure). So we can use the size of u64 in this overflow check. - If there are no snapshots, then there should be no snapshot names. Enforce this, and issue a warning if we encounter a header with no snapshots but a non-zero snap_names_len. - When saving the snapshot names into the header, be more direct in defining the offset in the on-disk structure from which they're being copied by using "snap_count" rather than "i" in the array index. - If an error occurs, the "snapc" and "snap_names" fields are freed at the end of the function. Make those fields be null pointers after they're freed, to be explicit that they are no longer valid. - Finally, move the definition of the local variable "i" to the innermost scope in which it's needed. Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- drivers/block/rbd.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 1222d58..3467693 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -494,14 +494,14 @@ static int rbd_header_from_disk(struct rbd_image_header *header, struct rbd_image_header_ondisk *ondisk, u32 allocated_snaps) { - u32 i, snap_count; + u32 snap_count; if (!rbd_dev_ondisk_valid(ondisk)) return -ENXIO; snap_count = le32_to_cpu(ondisk->snap_count); - if (snap_count > (UINT_MAX - sizeof(struct ceph_snap_context)) - / sizeof (*ondisk)) + if (snap_count > (SIZE_MAX - sizeof(struct ceph_snap_context)) + / sizeof (u64)) return -EINVAL; header->snapc = kmalloc(sizeof(struct ceph_snap_context) + snap_count * sizeof(u64), @@ -509,8 +509,8 @@ static int rbd_header_from_disk(struct rbd_image_header *header, if (!header->snapc) return -ENOMEM; - header->snap_names_len = le64_to_cpu(ondisk->snap_names_len); if (snap_count) { + header->snap_names_len = le64_to_cpu(ondisk->snap_names_len); header->snap_names = kmalloc(header->snap_names_len, GFP_KERNEL); if (!header->snap_names) @@ -520,6 +520,8 @@ static int rbd_header_from_disk(struct rbd_image_header *header, if (!header->snap_sizes) goto err_names; } else { + WARN_ON(ondisk->snap_names_len); + header->snap_names_len = 0; header->snap_names = NULL; header->snap_sizes = NULL; } @@ -544,6 +546,8 @@ static int rbd_header_from_disk(struct rbd_image_header *header, header->total_snaps = snap_count; if (snap_count && allocated_snaps == snap_count) { + int i; + for (i = 0; i < snap_count; i++) { header->snapc->snaps[i] = le64_to_cpu(ondisk->snaps[i].id); @@ -552,7 +556,7 @@ static int rbd_header_from_disk(struct rbd_image_header *header, } /* copy snapshot names */ - memcpy(header->snap_names, &ondisk->snaps[i], + memcpy(header->snap_names, &ondisk->snaps[snap_count], header->snap_names_len); } @@ -560,10 +564,14 @@ static int rbd_header_from_disk(struct rbd_image_header *header, err_sizes: kfree(header->snap_sizes); + header->snap_sizes = NULL; err_names: kfree(header->snap_names); + header->snap_names = NULL; err_snapc: kfree(header->snapc); + header->snapc = NULL; + return -ENOMEM; } -- 2.7.4