Description

In the Linux kernel, the following vulnerability has been resolved: power: supply: bq25980: Fix use-after-free in power_supply_changed() Using the `devm_` variant for requesting IRQ _before_ the `devm_` variant for allocating/registering the `power_supply` handle, means that the `power_supply` handle will be deallocated/unregistered _before_ the interrupt handler (since `devm_` naturally deallocates in reverse allocation order). This means that during removal, there is a race condition where an interrupt can fire just _after_ the `power_supply` handle has been freed, *but* just _before_ the corresponding unregistration of the IRQ handler has run. This will lead to the IRQ handler calling `power_supply_changed()` with a freed `power_supply` handle. Which usually crashes the system or otherwise silently corrupts the memory... Note that there is a similar situation which can also happen during `probe()`; the possibility of an interrupt firing _before_ registering the `power_supply` handle. This would then lead to the nasty situation of using the `power_supply` handle *uninitialized* in `power_supply_changed()`. Fix this racy use-after-free by making sure the IRQ is requested _after_ the registration of the `power_supply` handle.

References 8

• git.kernel.org https://git.kernel.org/stable/c/03d1e4ee4e6aa6d2966e883e4ca0e5be73bf1b7c
• git.kernel.org https://git.kernel.org/stable/c/0560a4b09c92e2ecaa883965cf6f9ca51c158ff9
• git.kernel.org https://git.kernel.org/stable/c/0de95d29d847c6217b7d5845e24a71a4aee7b359
• git.kernel.org https://git.kernel.org/stable/c/16875e3b7bc9e59bfa0acaf1e43f275a6f42a30f
• git.kernel.org https://git.kernel.org/stable/c/4aeaf03c17260415c2fdd55992f9ad4188d5455a
• git.kernel.org https://git.kernel.org/stable/c/5f0b1cb41906e86b64bf69f5ededb83b0d757c27
• git.kernel.org https://git.kernel.org/stable/c/86f93dfb23f5bf4f285c4256a7e909d222f7de56
• git.kernel.org https://git.kernel.org/stable/c/abea607ff2f62f4c0a5fb29f7fbdaaab163276a4

Remediation