Date: Mon, 19 Jun 2017 09:44:19 +0800 From: Jia-Ju Bai <baijiaju1990@163.com> To: freebsd-drivers@freebsd.org, freebsd-bugs@freebsd.org, freebsd-hackers@freebsd.org Cc: Jia-Ju Bai <baijiaju1990@163.com> Subject: [PATCH] mlx: Fix a possible sleep-under-mutex bug in mlx_alloccmd Message-ID: <20170619014419.43824-1-baijiaju1990@163.com>
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The driver may sleep under a mutex, and the function call path is:
mlx_attach [line 432: acquire the mutex]
mlx_enquire
mlx_alloccmd
bus_dmamap_create(BUS_DMA_WAITOK) --> may sleep
The possible fix of this bug is to replace "BUS_DMA_WAITOK" in bus_dmamap_create with "BUS_DMA_NOWAIT".
This bug is found by a static analysis tool written by myself, and it is
checked by my review of the FreeBSD code.
Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
---
sys/dev/mlx/mlx.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sys/dev/mlx/mlx.c b/sys/dev/mlx/mlx.c
index e3b09582a36..c2e8ba3c595 100644
--- a/sys/dev/mlx/mlx.c
+++ b/sys/dev/mlx/mlx.c
@@ -2426,7 +2426,8 @@ mlx_alloccmd(struct mlx_softc *sc)
mc = (struct mlx_command *)malloc(sizeof(*mc), M_DEVBUF, M_NOWAIT | M_ZERO);
if (mc != NULL) {
mc->mc_sc = sc;
- error = bus_dmamap_create(sc->mlx_buffer_dmat, 0, &mc->mc_dmamap);
+ error = bus_dmamap_create(sc->mlx_buffer_dmat, BUS_DMA_NOWAIT,
+ &mc->mc_dmamap);
if (error) {
free(mc, M_DEVBUF);
return(NULL);
--
2.13.0
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