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Change History

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

bpf: Reject sleepable kprobe_multi programs at attach time

kprobe.multi programs run in atomic/RCU context and cannot sleep.
However, bpf_kprobe_multi_link_attach() did not validate whether the
program being attached had the sleepable flag set, allowing sleepable
helpers such as bpf_copy_from_user() to be invoked from a non-sleepable
context.

This causes a "sleeping function called from invalid context" splat:

  BUG: sleeping function called from invalid context at ./include/linux/uaccess.h:169
  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1787, name: sudo
  preempt_count: 1, expected: 0
  RCU nest depth: 2, expected: 0

Fix this by rejecting sleepable programs early in
bpf_kprobe_multi_link_attach(), before any further processing.

https://git.kernel.org/stable/c/dc9a060d76c12b23c5f378ee115d5e5d03d8bbf3

https://git.kernel.org/stable/c/eb7024bfcc5f68ed11ed9dd4891a3073c15f04a8

https://git.kernel.org/stable/c/f952157e695fd434bdc05af63a703bb082a78717