| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix space cache corruption and potential double allocations
When testing space_cache v2 on a large set of machines, we encountered a
few symptoms:
1. "unable to add free space :-17" (EEXIST) errors.
2. Missing free space info items, sometimes caught with a "missing free
space info for X" error.
3. Double-accounted space: ranges that were allocated in the extent tree
and also marked as free in the free space tree, ranges that were
marked as allocated twice in the extent tree, or ranges that were
marked as free twice in the free space tree. If the latter made it
onto disk, the next reboot would hit the BUG_ON() in
add_new_free_space().
4. On some hosts with no on-disk corruption or error messages, the
in-memory space cache (dumped with drgn) disagreed with the free
space tree.
All of these symptoms have the same underlying cause: a race between
caching the free space for a block group and returning free space to the
in-memory space cache for pinned extents causes us to double-add a free
range to the space cache. This race exists when free space is cached
from the free space tree (space_cache=v2) or the extent tree
(nospace_cache, or space_cache=v1 if the cache needs to be regenerated).
struct btrfs_block_group::last_byte_to_unpin and struct
btrfs_block_group::progress are supposed to protect against this race,
but commit d0c2f4fa555e ("btrfs: make concurrent fsyncs wait less when
waiting for a transaction commit") subtly broke this by allowing
multiple transactions to be unpinning extents at the same time.
Specifically, the race is as follows:
1. An extent is deleted from an uncached block group in transaction A.
2. btrfs_commit_transaction() is called for transaction A.
3. btrfs_run_delayed_refs() -> __btrfs_free_extent() runs the delayed
ref for the deleted extent.
4. __btrfs_free_extent() -> do_free_extent_accounting() ->
add_to_free_space_tree() adds the deleted extent back to the free
space tree.
5. do_free_extent_accounting() -> btrfs_update_block_group() ->
btrfs_cache_block_group() queues up the block group to get cached.
block_group->progress is set to block_group->start.
6. btrfs_commit_transaction() for transaction A calls
switch_commit_roots(). It sets block_group->last_byte_to_unpin to
block_group->progress, which is block_group->start because the block
group hasn't been cached yet.
7. The caching thread gets to our block group. Since the commit roots
were already switched, load_free_space_tree() sees the deleted extent
as free and adds it to the space cache. It finishes caching and sets
block_group->progress to U64_MAX.
8. btrfs_commit_transaction() advances transaction A to
TRANS_STATE_SUPER_COMMITTED.
9. fsync calls btrfs_commit_transaction() for transaction B. Since
transaction A is already in TRANS_STATE_SUPER_COMMITTED and the
commit is for fsync, it advances.
10. btrfs_commit_transaction() for transaction B calls
switch_commit_roots(). This time, the block group has already been
cached, so it sets block_group->last_byte_to_unpin to U64_MAX.
11. btrfs_commit_transaction() for transaction A calls
btrfs_finish_extent_commit(), which calls unpin_extent_range() for
the deleted extent. It sees last_byte_to_unpin set to U64_MAX (by
transaction B!), so it adds the deleted extent to the space cache
again!
This explains all of our symptoms above:
* If the sequence of events is exactly as described above, when the free
space is re-added in step 11, it will fail with EEXIST.
* If another thread reallocates the deleted extent in between steps 7
and 11, then step 11 will silently re-add that space to the space
cache as free even though it is actually allocated. Then, if that
space is allocated *again*, the free space tree will be corrupted
(namely, the wrong item will be deleted).
* If we don't catch this free space tree corr
---truncated--- |
| Format Plugins versions 1.1.1 and earlier are affected by an Out-of-bounds Read vulnerability that could lead to memory exposure. An attacker could leverage this vulnerability to disclose sensitive information stored in memory. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by a Use After Free vulnerability that could lead to memory exposure. An attacker could leverage this vulnerability to disclose sensitive information. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by an Out-of-bounds Read vulnerability that could lead to memory exposure. An attacker could leverage this vulnerability to access sensitive memory information. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by a Heap-based Buffer Overflow vulnerability that could result in arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by a Heap-based Buffer Overflow vulnerability that could result in arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by an Out-of-bounds Read vulnerability that could lead to memory exposure. An attacker could leverage this vulnerability to disclose sensitive information stored in memory. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by an Out-of-bounds Read vulnerability that could lead to memory exposure. An attacker could leverage this vulnerability to disclose sensitive information stored in memory. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by an out-of-bounds read vulnerability when parsing a crafted file, which could result in a read past the end of an allocated memory structure. An attacker could leverage this vulnerability to execute code in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
| Format Plugins versions 1.1.1 and earlier are affected by an Out-of-bounds Read vulnerability that could lead to memory exposure. An attacker could leverage this vulnerability to disclose sensitive information stored in memory. Exploitation of this issue requires user interaction in that a victim must open a malicious file. |
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| The TwitterPosts WordPress plugin through 1.0.2 does not have CSRF check in place when updating its settings, which could allow attackers to make a logged in admin change them via a CSRF attack |
| The Sensei LMS WordPress plugin before 4.20.0 disclose all users of the blog including their email address to teachers on the students page |
| The Event Tickets with Ticket Scanner WordPress plugin before 2.3.8 does not sanitise and escape some parameters, which could allow users with a role as low as admin to perform Cross-Site Scripting attacks |
| The EventPrime WordPress plugin before 3.5.0 does not properly validate permissions when updating bookings, allowing users to change/cancel bookings for other users. Additionally, the feature is lacking a nonce. |
| The Responsive Gallery Grid WordPress plugin before 2.3.15 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Cross-Site Scripting attacks even when unfiltered_html is disallowed |
| The Advanced Cron Manager WordPress plugin before 2.5.7 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup) |
| The Carousel, Slider, Gallery by WP Carousel WordPress plugin before 2.6.9 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup) |
| The Smart Post Show WordPress plugin before 2.4.28 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup) |
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