On Fri, Aug 19, 2022 at 11:49:52AM +0200, Jens Wiklander wrote:
With special lengths supplied by user space, register_shm_helper() has an integer overflow when calculating the number of pages covered by a supplied user space memory region. This causes internal_get_user_pages_fast() a helper function of pin_user_pages_fast() to do a NULL pointer dereference.
[ 14.141620] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 [ 14.142556] Mem abort info: [ 14.142829] ESR = 0x0000000096000044 [ 14.143237] EC = 0x25: DABT (current EL), IL = 32 bits [ 14.143742] SET = 0, FnV = 0 [ 14.144052] EA = 0, S1PTW = 0 [ 14.144348] FSC = 0x04: level 0 translation fault [ 14.144767] Data abort info: [ 14.145053] ISV = 0, ISS = 0x00000044 [ 14.145394] CM = 0, WnR = 1 [ 14.145766] user pgtable: 4k pages, 48-bit VAs, pgdp=000000004278e000 [ 14.146279] [0000000000000010] pgd=0000000000000000, p4d=0000000000000000 [ 14.147435] Internal error: Oops: 96000044 [#1] PREEMPT SMP [ 14.148026] Modules linked in: [ 14.148595] CPU: 1 PID: 173 Comm: optee_example_a Not tainted 5.19.0 #11 [ 14.149204] Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 [ 14.149832] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 14.150481] pc : internal_get_user_pages_fast+0x474/0xa80 [ 14.151640] lr : internal_get_user_pages_fast+0x404/0xa80 [ 14.152408] sp : ffff80000a88bb30 [ 14.152711] x29: ffff80000a88bb30 x28: 0000fffff836d000 x27: 0000fffff836e000 [ 14.153580] x26: fffffc0000000000 x25: fffffc0000f4a1c0 x24: ffff00000289fb70 [ 14.154634] x23: ffff000002702e08 x22: 0000000000040001 x21: ffff8000097eec60 [ 14.155378] x20: 0000000000f4a1c0 x19: 00e800007d287f43 x18: 0000000000000000 [ 14.156215] x17: 0000000000000000 x16: 0000000000000000 x15: 0000fffff836cfb0 [ 14.157068] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 [ 14.157747] x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 [ 14.158576] x8 : ffff00000276ec80 x7 : 0000000000000000 x6 : 000000000000003f [ 14.159243] x5 : 0000000000000000 x4 : ffff000041ec4eac x3 : ffff000002774cb8 [ 14.159977] x2 : 0000000000000004 x1 : 0000000000000010 x0 : 0000000000000000 [ 14.160883] Call trace: [ 14.161166] internal_get_user_pages_fast+0x474/0xa80 [ 14.161763] pin_user_pages_fast+0x24/0x4c [ 14.162227] register_shm_helper+0x194/0x330 [ 14.162734] tee_shm_register_user_buf+0x78/0x120 [ 14.163290] tee_ioctl+0xd0/0x11a0 [ 14.163739] __arm64_sys_ioctl+0xa8/0xec [ 14.164227] invoke_syscall+0x48/0x114 [ 14.164653] el0_svc_common.constprop.0+0x44/0xec [ 14.165130] do_el0_svc+0x2c/0xc0 [ 14.165498] el0_svc+0x2c/0x84 [ 14.165847] el0t_64_sync_handler+0x1ac/0x1b0 [ 14.166258] el0t_64_sync+0x18c/0x190 [ 14.166878] Code: 91002318 11000401 b900f7e1 f9403be1 (f820d839) [ 14.167666] ---[ end trace 0000000000000000 ]---
Fix this by adding an overflow check when calculating the end of the memory range. Also add an explicit call to access_ok() in tee_shm_register_user_buf() to catch an invalid user space address early.
Fixes: 033ddf12bcf5 ("tee: add register user memory") Cc: stable@vger.kernel.org Reported-by: Nimish Mishra neelam.nimish@gmail.com Reported-by: Anirban Chakraborty ch.anirban00727@gmail.com Reported-by: Debdeep Mukhopadhyay debdeep.mukhopadhyay@gmail.com Suggested-by: Linus Torvalds torvalds@linuxfoundation.org Signed-off-by: Jens Wiklander jens.wiklander@linaro.org
This conflicts with 573ae4f13f63 ("tee: add overflow check in register_shm_helper()") in Linus's tree :(