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Subject[BUG] kernel: kcov: a possible sleep-in-atomic-context bug in kcov_ioctl()
The kernel may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

kernel/kcov.c, 237:
    vfree in kcov_put
kernel/kcov.c, 413:
    kcov_put in kcov_ioctl_locked
kernel/kcov.c, 427:
    kcov_ioctl_locked in kcov_ioctl
kernel/kcov.c, 426:
    spin_lock in kcov_ioctl

vfree() can sleep at runtime.

I am not sure how to properly fix this possible bug, so I only report it.
A possible way is to replace vfree() with kfree(), and replace related
calls to vmalloc() with kmalloc().

This bug is found by a static analysis tool STCheck written by myself.

Best wishes,
Jia-Ju Bai

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