CVE-2022-50080

Summary

In the Linux kernel, the following vulnerability has been resolved:

tee: add overflow check in register_shm_helper()

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:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 Modules linked in: CPU: 1 PID: 173 Comm: optee_example_a Not tainted 5.19.0 #11 Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 pc : internal_get_user_pages_fast+0x474/0xa80 Call trace: internal_get_user_pages_fast+0x474/0xa80 pin_user_pages_fast+0x24/0x4c register_shm_helper+0x194/0x330 tee_shm_register_user_buf+0x78/0x120 tee_ioctl+0xd0/0x11a0 __arm64_sys_ioctl+0xa8/0xec invoke_syscall+0x48/0x114

Fix this by adding an an explicit call to access_ok() in tee_shm_register_user_buf() to catch an invalid user space address early.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/b37e0f17653c00b586cdbcdf0dbca475358ecffd
• https://git.kernel.org/stable/c/965333345fe952cc7eebc8e3a565ffc709441af2
• https://git.kernel.org/stable/c/578c349570d2a912401963783b36e0ec7a25c053
• https://git.kernel.org/stable/c/c12f0e6126ad223806a365084e86370511654bf1
• https://git.kernel.org/stable/c/2f8e79a1a6128214cb9b205a9869341af5dfb16b
• https://git.kernel.org/stable/c/58c008d4d398f792ca67f35650610864725518fd
• https://git.kernel.org/stable/c/573ae4f13f630d6660008f1974c0a8a29c30e18a

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