In the Linux kernel, the following vulnerability has been resolved: firmware: armscmi: Fix double free in SMC transport cleanup path When the generic SCMI code tears down a channel, it calls the chanfree callback function, defined by each transport. Since multiple protocols might share the same transportinfo member, chanfree() might want to clean up the same member multiple times within the given SCMI transport implementation. In this case, it is SMC transport. This will lead to a NULL pointer dereference at the second time: | scmiprotocol scmidev.1: Enabled polling mode TX channel - protid:16 | arm-scmi firmware:scmi: SCMI Notifications - Core Enabled. | arm-scmi firmware:scmi: unable to communicate with SCMI | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 | Mem abort info: | ESR = 0x0000000096000004 | EC = 0x25: DABT (current EL), IL = 32 bits | SET = 0, FnV = 0 | EA = 0, S1PTW = 0 | FSC = 0x04: level 0 translation fault | Data abort info: | ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 | CM = 0, WnR = 0, TnD = 0, TagAccess = 0 | GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 | user pgtable: 4k pages, 48-bit VAs, pgdp=0000000881ef8000 | [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 | Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP | Modules linked in: | CPU: 4 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc2-00124-g455ef3d016c9-dirty #793 | Hardware name: FVP Base RevC (DT) | pstate: 61400009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) | pc : smcchanfree+0x3c/0x6c | lr : smcchanfree+0x3c/0x6c | Call trace: | smcchanfree+0x3c/0x6c | idrforeach+0x68/0xf8 | scmicleanupchannels.isra.0+0x2c/0x58 | scmiprobe+0x434/0x734 | platformprobe+0x68/0xd8 | reallyprobe+0x110/0x27c | _driverprobedevice+0x78/0x12c | driverprobedevice+0x3c/0x118 | _driverattach+0x74/0x128 | busforeachdev+0x78/0xe0 | driverattach+0x24/0x30 | busadddriver+0xe4/0x1e8 | driverregister+0x60/0x128 | _platformdriverregister+0x28/0x34 | scmidriverinit+0x84/0xc0 | dooneinitcall+0x78/0x33c | kernelinitfreeable+0x2b8/0x51c | kernelinit+0x24/0x130 | retfromfork+0x10/0x20 | Code: f0004701 910a0021 aa1403e5 97b91c70 (b9400280) | ---[ end trace 0000000000000000 ]--- Simply check for the struct pointer being NULL before trying to access its members, to avoid this situation. This was found when a transport doesn't really work (for instance no SMC service), the probe routines then tries to clean up, and triggers a crash.