Problem

[Amar Lior]

Hi all,

I found a bug that cause the kernel to lockup.

The problem is in mm/shmem.c do_shmem_file_read() (the tmpfs)

at line 959 there is a call to file_read_actor(desc, page, offset, nr);

The problem is that inside the function file_read_actor() desc->error is
set to -EFAULT (this happens when the buffer supplied by the user for the 
read is wrong)
but there is no check right after the return from file_read_actor() to
test this situation.

The result is that the desc->count field always stay the same and the
while loop in do_shmem_file_read never end and the kernel locksup.

The fix is very simple just add the following line after the call to 
file_read_actor():

-------------------
if(desc->error)
        break
-------------------

If you need any other info please mail me

Regards

--lior

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Lior Amar                       Distributed Computing Lab MOSIX
E-mail  : [e-mail]                           
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