On Fri, Oct 21, 2022 at 02:33:09PM +0200, Ard Biesheuvel wrote: > The TPM code registers put_device() as a devm cleanup handler, and casts > the reference to the right function pointer type for this to be > permitted by the compiler. > > However, under kCFI, this is rejected at runtime, resulting in a splat > like > > CFI failure at devm_action_release+0x24/0x3c (target: put_device+0x0/0x24; expected type: 0xa488ebfc) > Internal error: Oops - CFI: 0000000000000000 [#1] PREEMPT SMP > Modules linked in: ... > CPU: 20 PID: 454 Comm: systemd-udevd Not tainted 6.1.0-rc1+ #51 > Hardware name: Socionext SynQuacer E-series DeveloperBox, BIOS build #1 Oct 3 2022 > pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : devm_action_release+0x24/0x3c > lr : devres_release_all+0xb4/0x114 > sp : ffff800009bb3630 > x29: ffff800009bb3630 x28: 0000000000000000 x27: 0000000000000011 > x26: ffffaa6f9922c0c8 x25: 0000000000000002 x24: 000000000000000f > x23: ffff800009bb3648 x22: ffff7aefc3be2100 x21: ffff7aefc3be2e00 > x20: 0000000000000005 x19: ffff7aefc1e1ec10 x18: ffff800009af70a8 > x17: 00000000a488ebfc x16: 0000000094ee7df3 x15: 0000000000000000 > x14: 4075c5c2ef7affff x13: e46a91c5c5e2ef42 x12: ffff7aefc2c57540 > x11: 0000000000000001 x10: 0000000000000001 x9 : 0000000100000000 > x8 : ffffaa6fa09b39b4 x7 : 7f7f7f7f7f7f7f7f x6 : 8000000000000000 > x5 : 000000008020000e x4 : ffff7aefc2c57500 x3 : ffff800009bb3648 > x2 : ffff800009bb3648 x1 : ffff7aefc3be2e80 x0 : ffff7aefc3bb7000 > Call trace: > devm_action_release+0x24/0x3c > devres_release_all+0xb4/0x114 > really_probe+0xb0/0x49c > __driver_probe_device+0x114/0x180 > driver_probe_device+0x48/0x1ec > __driver_attach+0x118/0x284 > bus_for_each_dev+0x94/0xe4 > driver_attach+0x24/0x34 > bus_add_driver+0x10c/0x220 > driver_register+0x78/0x118 > __platform_driver_register+0x24/0x34 > init_module+0x20/0xfe4 [tpm_tis_synquacer] > do_one_initcall+0xd4/0x248 > do_init_module+0x44/0x28c > load_module+0x16b4/0x1920 > > Fix this by going through a helper function of the correct type. > > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
