6.10-stable review patch. If anyone has any objections, please let me know.
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From: Martin Karsten mkarsten@uwaterloo.ca
commit b9ca079dd6b09e08863aa998edf5c47597806c05 upstream.
A struct eventpoll's busy_poll_usecs field can be modified via a user ioctl at any time. All reads of this field should be annotated with READ_ONCE.
Fixes: 85455c795c07 ("eventpoll: support busy poll per epoll instance") Cc: stable@vger.kernel.org Signed-off-by: Martin Karsten mkarsten@uwaterloo.ca Link: https://lore.kernel.org/r/20240806123301.167557-1-jdamato@fastly.com Reviewed-by: Joe Damato jdamato@fastly.com Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/eventpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 6c0a1e9715ea..145f5349c612 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -420,7 +420,7 @@ static bool busy_loop_ep_timeout(unsigned long start_time,
static bool ep_busy_loop_on(struct eventpoll *ep) { - return !!ep->busy_poll_usecs || net_busy_loop_on(); + return !!READ_ONCE(ep->busy_poll_usecs) || net_busy_loop_on(); }
static bool ep_busy_loop_end(void *p, unsigned long start_time)