CVE-2023-53813
0.03%V4
2025-12-09
01h16 +00:00
01h16 +00:00
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Luôn được thông báo về mọi thay đổi đối với một CVE cụ thể.
Mô tả CVE
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix rbtree traversal bug in ext4_mb_use_preallocated
During allocations, while looking for preallocations(PA) in the per
inode rbtree, we can't do a direct traversal of the tree because
ext4_mb_discard_group_preallocation() can paralelly mark the pa deleted
and that can cause direct traversal to skip some entries. This was
leading to a BUG_ON() being hit [1] when we missed a PA that could satisfy
our request and ultimately tried to create a new PA that would overlap
with the missed one.
To makes sure we handle that case while still keeping the performance of
the rbtree, we make use of the fact that the only pa that could possibly
overlap the original goal start is the one that satisfies the below
conditions:
1. It must have it's logical start immediately to the left of
(ie less than) original logical start.
2. It must not be deleted
To find this pa we use the following traversal method:
1. Descend into the rbtree normally to find the immediate neighboring
PA. Here we keep descending irrespective of if the PA is deleted or if
it overlaps with our request etc. The goal is to find an immediately
adjacent PA.
2. If the found PA is on right of original goal, use rb_prev() to find
the left adjacent PA.
3. Check if this PA is deleted and keep moving left with rb_prev() until
a non deleted PA is found.
4. This is the PA we are looking for. Now we can check if it can satisfy
the original request and proceed accordingly.
This approach also takes care of having deleted PAs in the tree.
(While we are at it, also fix a possible overflow bug in calculating the
end of a PA)
[1] https://lore.kernel.org/linux-ext4/CA+G9fYv2FRpLqBZf34ZinR8bU2_ZRAUOjKAD3+tKRFaEQHtt8Q@mail.gmail.com/
Thông tin CVE
EPSS
EPSS là mô hình tính điểm dự đoán khả năng một lỗ hổng bị khai thác.
Điểm EPSS
Mô hình EPSS tạo ra điểm xác suất từ 0 đến 1 (0 đến 100%). Điểm càng cao, xác suất một lỗ hổng bị khai thác càng lớn.
Phân vị EPSS
Phân vị được dùng để xếp hạng CVE theo điểm EPSS. Ví dụ, một CVE ở phân vị thứ 95 theo điểm EPSS có nhiều khả năng bị khai thác hơn 95% CVE khác. Do đó, phân vị được dùng để so sánh điểm EPSS của một CVE với các CVE khác.
