CVE-2024-47688

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

driver core: Fix a potential null-ptr-deref in module_add_driver()

Inject fault while probing of-fpga-region, if kasprintf() fails in module_add_driver(), the second sysfs_remove_link() in exit path will cause null-ptr-deref as below because kernfs_name_hash() will call strlen() with NULL driver_name.

Fix it by releasing resources based on the exit path sequence.

 KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
 Mem abort info:
   ESR = 0x0000000096000005
   EC = 0x25: DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
   FSC = 0x05: level 1 translation fault
 Data abort info:
   ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
 [dfffffc000000000] address between user and kernel address ranges
 Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
 Dumping ftrace buffer:
    (ftrace buffer empty)
 Modules linked in: of_fpga_region(+) fpga_region fpga_bridge cfg80211 rfkill 8021q garp mrp stp llc ipv6 [last unloaded: of_fpga_region]
 CPU: 2 UID: 0 PID: 2036 Comm: modprobe Not tainted 6.11.0-rc2-g6a0e38264012 #295
 Hardware name: linux,dummy-virt (DT)
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : strlen+0x24/0xb0
 lr : kernfs_name_hash+0x1c/0xc4
 sp : ffffffc081f97380
 x29: ffffffc081f97380 x28: ffffffc081f97b90 x27: ffffff80c821c2a0
 x26: ffffffedac0be418 x25: 0000000000000000 x24: ffffff80c09d2000
 x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000
 x20: 0000000000000000 x19: 0000000000000000 x18: 0000000000001840
 x17: 0000000000000000 x16: 0000000000000000 x15: 1ffffff8103f2e42
 x14: 00000000f1f1f1f1 x13: 0000000000000004 x12: ffffffb01812d61d
 x11: 1ffffff01812d61c x10: ffffffb01812d61c x9 : dfffffc000000000
 x8 : 0000004fe7ed29e4 x7 : ffffff80c096b0e7 x6 : 0000000000000001
 x5 : ffffff80c096b0e0 x4 : 1ffffffdb990efa2 x3 : 0000000000000000
 x2 : 0000000000000000 x1 : dfffffc000000000 x0 : 0000000000000000
 Call trace:
  strlen+0x24/0xb0
  kernfs_name_hash+0x1c/0xc4
  kernfs_find_ns+0x118/0x2e8
  kernfs_remove_by_name_ns+0x80/0x100
  sysfs_remove_link+0x74/0xa8
  module_add_driver+0x278/0x394
  bus_add_driver+0x1f0/0x43c
  driver_register+0xf4/0x3c0
  __platform_driver_register+0x60/0x88
  of_fpga_region_init+0x20/0x1000 [of_fpga_region]
  do_one_initcall+0x110/0x788
  do_init_module+0x1dc/0x5c8
  load_module+0x3c38/0x4cac
  init_module_from_file+0xd4/0x128
  idempotent_init_module+0x2cc/0x528
  __arm64_sys_finit_module+0xac/0x100
  invoke_syscall+0x6c/0x258
  el0_svc_common.constprop.0+0x160/0x22c
  do_el0_svc+0x44/0x5c
  el0_svc+0x48/0xb8
  el0t_64_sync_handler+0x13c/0x158
  el0t_64_sync+0x190/0x194
 Code: f2fbffe1 a90157f4 12000802 aa0003f5 (38e16861)
 ---[ end trace 0000000000000000 ]---
 Kernel panic - not syncing: Oops: Fatal exception

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/18ec12c97b39ff6aa15beb8d2b25d15cd44b87d8
• https://git.kernel.org/stable/c/4b5d48b7a29cc6d508121a4b4e0c97a891e5273c
• https://git.kernel.org/stable/c/b8e45b910525704010d10c9dcbf2abf3005aa97c
• https://git.kernel.org/stable/c/dcb9d581dee4c23f2378b6650511ece80dda4e2f