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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2025-38614

eventpoll: Fix semi-unbounded recursion

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: eventpoll: Fix semi-unbounded recursion Ensure that epoll instances can never form a graph deeper than EP_MAX_NESTS+1 links. Currently, ep_loop_check_proc() ensures that the graph is loop-free and does some recursion depth checks, but those recursion depth checks don't limit the depth of the resulting tree for two reasons: - They don't look upwards in the tree. - If there are multiple downwards paths of different lengths, only one of the paths is actually considered for the depth check since commit 28d82dc1c4ed ("epoll: limit paths"). Essentially, the current recursion depth check in ep_loop_check_proc() just serves to prevent it from recursing too deeply while checking for loops. A more thorough check is done in reverse_path_check() after the new graph edge has already been created; this checks, among other things, that no paths going upwards from any non-epoll file with a length of more than 5 edges exist. However, this check does not apply to non-epoll files. As a result, it is possible to recurse to a depth of at least roughly 500, tested on v6.15. (I am unsure if deeper recursion is possible; and this may have changed with commit 8c44dac8add7 ("eventpoll: Fix priority inversion problem").) To fix it: 1. In ep_loop_check_proc(), note the subtree depth of each visited node, and use subtree depths for the total depth calculation even when a subtree has already been visited. 2. Add ep_get_upwards_depth_proc() for similarly determining the maximum depth of an upwards walk. 3. In ep_loop_check(), use these values to limit the total path length between epoll nodes to EP_MAX_NESTS edges.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e to < 71379495ab70eaba19224bd71b5b9b399eb85e04affected
  • 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e to < 1b13b033062824495554e836a1ff5f85ccf6b039affected
  • 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e to < 2a0c0c974bea9619c6f41794775ae4b97530e0e6affected
  • 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e to < 7a2125962c42d5336ca0495a9ce4cb38a63e9161affected
  • 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e to < ea5f97dbdcb1651581a22bd10afd2f0dd9dc11d6affected
  • 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e to < 3542c90797bc3ab83ebab54b737d751cf3682036affected
  • 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e to < f2e467a48287c868818085aa35389a224d226732affected
  • 8216e1a0d47cae06a75c42346f19dffe14e42d57affected
  • 28a92748aa4bc57d35e7b079498b0ac2e7610a37affected
  • 7eebcd4792c5a341559aed327b6afecbb1c46402affected
  • 0eccd188cfeaf857a26f2d72941d27d298cf6a54affected
  • a72affdbb09f3f24f64ffcbbdf62c2e57c58f379affected
  • 2.6.32.30 to < 2.6.33affected
  • 2.6.33.8 to < 2.6.34affected
  • 2.6.34.10 to < 2.6.35affected
  • 2.6.35.12 to < 2.6.36affected
  • 2.6.37.3 to < 2.6.38affected

Linux Linux

Default version status: affected

  • 2.6.38affected
  • 0 to < 2.6.38unaffected
  • 5.15.190 to ≤ 5.15.*unaffected
  • 6.1.149 to ≤ 6.1.*unaffected
  • 6.6.103 to ≤ 6.6.*unaffected
  • 6.12.43 to ≤ 6.12.*unaffected
  • 6.15.11 to ≤ 6.15.*unaffected
  • 6.16.1 to ≤ 6.16.*unaffected
  • 6.17 to ≤ *unaffected

References