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CVE
PUBLISHED

CVE-2024-39476

md/raid5: fix deadlock that raid5d() wait for itself to clear MD_SB_CHANGE_PENDING

AssignerLinux
Reserved2024-06-25
Published2024-07-05
Updated2024-07-15

Description

In the Linux kernel, the following vulnerability has been resolved: md/raid5: fix deadlock that raid5d() wait for itself to clear MD_SB_CHANGE_PENDING Xiao reported that lvm2 test lvconvert-raid-takeover.sh can hang with small possibility, the root cause is exactly the same as commit bed9e27baf52 ("Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"") However, Dan reported another hang after that, and junxiao investigated the problem and found out that this is caused by plugged bio can't issue from raid5d(). Current implementation in raid5d() has a weird dependence: 1) md_check_recovery() from raid5d() must hold 'reconfig_mutex' to clear MD_SB_CHANGE_PENDING; 2) raid5d() handles IO in a deadloop, until all IO are issued; 3) IO from raid5d() must wait for MD_SB_CHANGE_PENDING to be cleared; This behaviour is introduce before v2.6, and for consequence, if other context hold 'reconfig_mutex', and md_check_recovery() can't update super_block, then raid5d() will waste one cpu 100% by the deadloop, until 'reconfig_mutex' is released. Refer to the implementation from raid1 and raid10, fix this problem by skipping issue IO if MD_SB_CHANGE_PENDING is still set after md_check_recovery(), daemon thread will be woken up when 'reconfig_mutex' is released. Meanwhile, the hang problem will be fixed as well.

Product status

Default status
unaffected

f3d55bd5b7b9 before b32aa95843ca
affected

1c00bb624cd0 before 634ba3c97ec4
affected

782b3e71c957 before aa64464c8f4d
affected

9e86dffd0b02 before 098d54934814
affected

5e2cf333b7bd before 3f8d5e802d4c
affected

5e2cf333b7bd before cd2538e5af49
affected

5e2cf333b7bd before e332a12f65d8
affected

5e2cf333b7bd before 151f66bb618d
affected

Default status
affected

6.1
affected

Any version before 6.1
unaffected

4.19.316
unaffected

5.4.278
unaffected

5.10.219
unaffected

5.15.161
unaffected

6.1.94
unaffected

6.6.34
unaffected

6.9.5
unaffected

6.10
unaffected

References

https://git.kernel.org/stable/c/b32aa95843cac6b12c2c014d40fca18aef24a347

https://git.kernel.org/stable/c/634ba3c97ec413cb10681c7b196db43ee461ecf4

https://git.kernel.org/stable/c/aa64464c8f4d2ab92f6d0b959a1e0767b829d787

https://git.kernel.org/stable/c/098d54934814dd876963abfe751c3b1cf7fbe56a

https://git.kernel.org/stable/c/3f8d5e802d4cedd445f9a89be8c3fd2d0e99024b

https://git.kernel.org/stable/c/cd2538e5af495b3c747e503db346470fc1ffc447

https://git.kernel.org/stable/c/e332a12f65d8fed8cf63bedb4e9317bb872b9ac7

https://git.kernel.org/stable/c/151f66bb618d1fd0eeb84acb61b4a9fa5d8bb0fa

cve.org CVE-2024-39476

nvd.nist.gov CVE-2024-39476

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