CWE
908
Advisory Published
Updated

CVE-2024-50273: btrfs: reinitialize delayed ref list after deleting it from the list

First published: Tue Nov 19 2024(Updated: )

In the Linux kernel, the following vulnerability has been resolved: btrfs: reinitialize delayed ref list after deleting it from the list At insert_delayed_ref() if we need to update the action of an existing ref to BTRFS_DROP_DELAYED_REF, we delete the ref from its ref head's ref_add_list using list_del(), which leaves the ref's add_list member not reinitialized, as list_del() sets the next and prev members of the list to LIST_POISON1 and LIST_POISON2, respectively. If later we end up calling drop_delayed_ref() against the ref, which can happen during merging or when destroying delayed refs due to a transaction abort, we can trigger a crash since at drop_delayed_ref() we call list_empty() against the ref's add_list, which returns false since the list was not reinitialized after the list_del() and as a consequence we call list_del() again at drop_delayed_ref(). This results in an invalid list access since the next and prev members are set to poison pointers, resulting in a splat if CONFIG_LIST_HARDENED and CONFIG_DEBUG_LIST are set or invalid poison pointer dereferences otherwise. So fix this by deleting from the list with list_del_init() instead.

Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Affected SoftwareAffected VersionHow to fix
Linux Linux kernel>=4.10<4.19.324
Linux Linux kernel>=4.20<5.4.286
Linux Linux kernel>=5.5<5.10.230
Linux Linux kernel>=5.11<5.15.172
Linux Linux kernel>=5.16<6.1.117
Linux Linux kernel>=6.2<6.6.61
Linux Linux kernel>=6.7<6.11.8
Linux Linux kernel=6.12-rc1
Linux Linux kernel=6.12-rc2
Linux Linux kernel=6.12-rc3
Linux Linux kernel=6.12-rc4
Linux Linux kernel=6.12-rc5
Linux Linux kernel=6.12-rc6

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