UPSTREAM: sched/psi: Fix OOB write when writing 0 bytes to PSI files

Issuing write() with count parameter set to 0 on any file under
/proc/pressure/ will cause an OOB write because of the access to
buf[buf_size-1] when NUL-termination is performed. Fix this by checking
for buf_size to be non-zero.

Signed-off-by: Suren Baghdasaryan <>
Signed-off-by: Peter Zijlstra (Intel) <>
Signed-off-by: Ingo Molnar <>
Acked-by: Johannes Weiner <>

(cherry picked from commit 6fcca0fa48118e6d63733eb4644c6cd880c15b8f)

Bug: 148159562
Signed-off-by: Suren Baghdasaryan <>
Change-Id: I9ec7acfc6e1083c677a95b0ea1c559ab50152873
1 file changed