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authorEugeni Dodonov <>2011-11-10 13:55:15 -0200
committerRohan Somvanshi <>2012-01-11 09:22:29 -0800
commit23cd227590341dc0573d6d07b162b965e9fc47c6 (patch)
treec5391c261470948656f90c4112b4a2adb5c6466a /block
parent21eb1b986d9eff984552538196282ee066f001c9 (diff)
drm/i915: prevent division by zero when asking for chipset power
commit 4ed0b577457eb6aeb7cdc7e7316576e63d15abb2 upstream. This prevents an in-kernel division by zero which happens when we are asking for i915_chipset_val too quickly, or within a race condition between the power monitoring thread and userspace accesses via debugfs. The issue can be reproduced easily via the following command: while ``; do cat /sys/kernel/debug/dri/0/i915_emon_status; done This is particularly dangerous because it can be triggered by a non-privileged user by just reading the debugfs entry. This issue was also found independently by Konstantin Belousov <>, who proposed a similar patch. Reported-by: Konstantin Belousov <> Acked-by: Jesse Barnes <> Acked-by: Keith Packard <> Reviewed-by: Chris Wilson <> Signed-off-by: Eugeni Dodonov <> Signed-off-by: Keith Packard <> Signed-off-by: Greg Kroah-Hartman <> Change-Id: Ic86534499300b66168ad29ac08ab1e1f987de909 Reviewed-on: http://git-master/r/74160 Reviewed-by: Varun Wadekar <> Tested-by: Varun Wadekar <>
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