"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nfirmware: arm_scmi: Fix double free in SMC transport cleanup path\n\nWhen the generic SCMI code tears down a channel, it calls the chan_free\ncallback function, defined by each transport. Since multiple protocols\nmight share the same transport_info member, chan_free() might want to\nclean up the same member multiple times within the given SCMI transport\nimplementation. In this case, it is SMC transport. This will lead to a NULL\npointer dereference at the second time:\n\n | scmi_protocol scmi_dev.1: Enabled polling mode TX channel - prot_id:16\n | arm-scmi firmware:scmi: SCMI Notifications - Core Enabled.\n | arm-scmi firmware:scmi: unable to communicate with SCMI\n | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000\n | Mem abort info:\n | ESR = 0x0000000096000004\n | EC = 0x25: DABT (current EL), IL = 32 bits\n | SET = 0, FnV = 0\n | EA = 0, S1PTW = 0\n | FSC = 0x04: level 0 translation fault\n | Data abort info:\n | ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000\n | CM = 0, WnR = 0, TnD = 0, TagAccess = 0\n | GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0\n | user pgtable: 4k pages, 48-bit VAs, pgdp=0000000881ef8000\n | [0000000000000000] pgd=0000000000000000, p4d=0000000000000000\n | Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP\n | Modules linked in:\n | CPU: 4 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc2-00124-g455ef3d016c9-dirty #793\n | Hardware name: FVP Base RevC (DT)\n | pstate: 61400009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n | pc : smc_chan_free+0x3c/0x6c\n | lr : smc_chan_free+0x3c/0x6c\n | Call trace:\n | smc_chan_free+0x3c/0x6c\n | idr_for_each+0x68/0xf8\n | scmi_cleanup_channels.isra.0+0x2c/0x58\n | scmi_probe+0x434/0x734\n | platform_probe+0x68/0xd8\n | really_probe+0x110/0x27c\n | __driver_probe_device+0x78/0x12c\n | driver_probe_device+0x3c/0x118\n | __driver_attach+0x74/0x128\n | bus_for_each_dev+0x78/0xe0\n | driver_attach+0x24/0x30\n | bus_add_driver+0xe4/0x1e8\n | driver_register+0x60/0x128\n | __platform_driver_register+0x28/0x34\n | scmi_driver_init+0x84/0xc0\n | do_one_initcall+0x78/0x33c\n | kernel_init_freeable+0x2b8/0x51c\n | kernel_init+0x24/0x130\n | ret_from_fork+0x10/0x20\n | Code: f0004701 910a0021 aa1403e5 97b91c70 (b9400280)\n | ---[ end trace 0000000000000000 ]---\n\nSimply check for the struct pointer being NULL before trying to access\nits members, to avoid this situation.\n\nThis was found when a transport doesn't really work (for instance no SMC\nservice), the probe routines then tries to clean up, and triggers a crash."
