nilfs2: fix potential null-ptr-deref in nilfs_btree_insert()

Summary

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential null-ptr-deref in nilfs_btree_insert() Patch series "nilfs2: fix potential issues with empty b-tree nodes". This series addresses three potential issues with empty b-tree nodes that can occur with corrupted filesystem images, including one recently discovered by syzbot. This patch (of 3): If a b-tree is broken on the device, and the b-tree height is greater than 2 (the level of the root node is greater than 1) even if the number of child nodes of the b-tree root is 0, a NULL pointer dereference occurs in nilfs_btree_prepare_insert(), which is called from nilfs_btree_insert(). This is because, when the number of child nodes of the b-tree root is 0, nilfs_btree_do_lookup() does not set the block buffer head in any of path[x].bp_bh, leaving it as the initial value of NULL, but if the level of the b-tree root node is greater than 1, nilfs_btree_get_nonroot_node(), which accesses the buffer memory of path[x].bp_bh, is called. Fix this issue by adding a check to nilfs_btree_root_broken(), which performs sanity checks when reading the root node from the device, to detect this inconsistency. Thanks to Lizhi Xu for trying to solve the bug and clarifying the cause early on.

Timeline

1. Oct 21, 2024, 11:53 AM UTCCVE published
2. Oct 21, 2024, 1:04 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 15, 2026, 12:51 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in 2b78e9df10fb7f4e9d3d7a18417dd72fbbc1dfd0; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in 1d94dbdfbb64cc48d10dec65cc3c4fbf2497b343; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in 24bf40740a3da6b4056721da34997ae6938f3da1; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in 73d23ecf234b7a6d47fb883f2dabe10e3230b31d; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in f68523e0f26faade18833fbef577a4295d8e2c94; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in 21839b6fbc3c41b3e374ecbdb0cabbbb2c53cf34; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in db73500d3f0e558eb642aae1d4782e7726b4a03f; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in 3644554d308ddf2669e459a1551a7edf60b2d62b; From 17c76b0104e4a6513983777e1a17e0297a12b0c4 · fixed in 9403001ad65ae4f4c5de368bdda3a0636b51d51a

• Linux Linux

  2.6.30

• KernelLinux

  From 2.6.30 · fixed in 4.19.323; From 4.20.0 · fixed in 5.4.285; From 5.5.0 · fixed in 5.10.227; From 5.11.0 · fixed in 5.15.168; From 5.16.0 · fixed in 6.1.113; From 6.2.0 · fixed in 6.6.54; From 6.7.0 · fixed in 6.10.13; From 6.11.0 · fixed in 6.11.2

References 9