lib/sg_pool.c | 16 ++-------------- 1 file changed, 2 insertions(+), 14 deletions(-)
sg_alloc_table_chained() is called by several drivers, but if it is
called before sg_pool_init(), it results in a NULL pointer dereference
in sg_pool_alloc().
Since commit 9b1d6c895002 ("lib: scatterlist: move SG pool code from
SCSI driver to lib/sg_pool.c"), we rely on module_init(sg_pool_init)
is invoked before other module_init calls but this assumption is
fragile.
I slightly changed the link order while Kbuild refactoring Kbuild,
then uncovered this issue. I should keep the current link order, but
depending on a specific call order among module_init is so fragine.
We usually define the init order by specifying *_initcall correctly,
or delay the driver probing by returning -EPROBE_DEFER.
Change module_initcall() to subsys_initcall(), and also delete the
pointless module_exit() because lib/sg_pool.c is always compiled as
built-in. (CONFIG_SG_POOL is bool)
Link: https://lore.kernel.org/all/20220921043946.GA1355561@roeck-us.net/
Link: https://lore.kernel.org/all/8e70837d-d859-dfb2-bf7f-83f8b31467bc@samsung.com/
Fixes: 9b1d6c895002 ("lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
I am sending this to DMA subsystem because I did not find
a corresponding one for lib/sg_pool.c
lib/sg_pool.c | 16 ++--------------
1 file changed, 2 insertions(+), 14 deletions(-)
diff --git a/lib/sg_pool.c b/lib/sg_pool.c
index a0b1a52cd6f7..9bfe60ca3f37 100644
--- a/lib/sg_pool.c
+++ b/lib/sg_pool.c
@@ -1,5 +1,5 @@
// SPDX-License-Identifier: GPL-2.0-only
-#include <linux/module.h>
+#include <linux/init.h>
#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/slab.h>
@@ -177,16 +177,4 @@ static __init int sg_pool_init(void)
return -ENOMEM;
}
-static __exit void sg_pool_exit(void)
-{
- int i;
-
- for (i = 0; i < SG_MEMPOOL_NR; i++) {
- struct sg_pool *sgp = sg_pools + i;
- mempool_destroy(sgp->pool);
- kmem_cache_destroy(sgp->slab);
- }
-}
-
-module_init(sg_pool_init);
-module_exit(sg_pool_exit);
+subsys_initcall(sg_pool_init);
--
2.34.1
Thanks, applied with the typo fixes included.
On 23.09.2022 13:38, Masahiro Yamada wrote: > sg_alloc_table_chained() is called by several drivers, but if it is > called before sg_pool_init(), it results in a NULL pointer dereference > in sg_pool_alloc(). > > Since commit 9b1d6c895002 ("lib: scatterlist: move SG pool code from > SCSI driver to lib/sg_pool.c"), we rely on module_init(sg_pool_init) > is invoked before other module_init calls but this assumption is > fragile. > > I slightly changed the link order while Kbuild refactoring Kbuild, > then uncovered this issue. I should keep the current link order, but > depending on a specific call order among module_init is so fragine. > > We usually define the init order by specifying *_initcall correctly, > or delay the driver probing by returning -EPROBE_DEFER. > > Change module_initcall() to subsys_initcall(), and also delete the > pointless module_exit() because lib/sg_pool.c is always compiled as > built-in. (CONFIG_SG_POOL is bool) > > Link: https://lore.kernel.org/all/20220921043946.GA1355561@roeck-us.net/ > Link: https://lore.kernel.org/all/8e70837d-d859-dfb2-bf7f-83f8b31467bc@samsung.com/ > Fixes: 9b1d6c895002 ("lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c") > Reported-by: Guenter Roeck <linux@roeck-us.net> > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > --- > > I am sending this to DMA subsystem because I did not find > a corresponding one for lib/sg_pool.c Feel free to add: Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> > lib/sg_pool.c | 16 ++-------------- > 1 file changed, 2 insertions(+), 14 deletions(-) > > diff --git a/lib/sg_pool.c b/lib/sg_pool.c > index a0b1a52cd6f7..9bfe60ca3f37 100644 > --- a/lib/sg_pool.c > +++ b/lib/sg_pool.c > @@ -1,5 +1,5 @@ > // SPDX-License-Identifier: GPL-2.0-only > -#include <linux/module.h> > +#include <linux/init.h> > #include <linux/scatterlist.h> > #include <linux/mempool.h> > #include <linux/slab.h> > @@ -177,16 +177,4 @@ static __init int sg_pool_init(void) > return -ENOMEM; > } > > -static __exit void sg_pool_exit(void) > -{ > - int i; > - > - for (i = 0; i < SG_MEMPOOL_NR; i++) { > - struct sg_pool *sgp = sg_pools + i; > - mempool_destroy(sgp->pool); > - kmem_cache_destroy(sgp->slab); > - } > -} > - > -module_init(sg_pool_init); > -module_exit(sg_pool_exit); > +subsys_initcall(sg_pool_init); Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
On 2022-09-23 12:38, Masahiro Yamada wrote: > sg_alloc_table_chained() is called by several drivers, but if it is > called before sg_pool_init(), it results in a NULL pointer dereference > in sg_pool_alloc(). > > Since commit 9b1d6c895002 ("lib: scatterlist: move SG pool code from > SCSI driver to lib/sg_pool.c"), we rely on module_init(sg_pool_init) > is invoked before other module_init calls but this assumption is > fragile. > > I slightly changed the link order while Kbuild refactoring Kbuild, > then uncovered this issue. I should keep the current link order, but > depending on a specific call order among module_init is so fragine. > > We usually define the init order by specifying *_initcall correctly, > or delay the driver probing by returning -EPROBE_DEFER. > > Change module_initcall() to subsys_initcall(), and also delete the > pointless module_exit() because lib/sg_pool.c is always compiled as > built-in. (CONFIG_SG_POOL is bool) Makes sense to me. Short of having some cool-but-impractically-complex system to derive a dependency graph from the config and compute an initcall order from that, initialising helper library code at an earlier step than drivers certainly seems like the next-best option, and subsys doesn't seem inappropriate for the nature of this code. FWIW, Reviewed-by: Robin Murphy <robin.murphy@arm.com> > Link: https://lore.kernel.org/all/20220921043946.GA1355561@roeck-us.net/ > Link: https://lore.kernel.org/all/8e70837d-d859-dfb2-bf7f-83f8b31467bc@samsung.com/ > Fixes: 9b1d6c895002 ("lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c") > Reported-by: Guenter Roeck <linux@roeck-us.net> > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > --- > > I am sending this to DMA subsystem because I did not find > a corresponding one for lib/sg_pool.c > > lib/sg_pool.c | 16 ++-------------- > 1 file changed, 2 insertions(+), 14 deletions(-) > > diff --git a/lib/sg_pool.c b/lib/sg_pool.c > index a0b1a52cd6f7..9bfe60ca3f37 100644 > --- a/lib/sg_pool.c > +++ b/lib/sg_pool.c > @@ -1,5 +1,5 @@ > // SPDX-License-Identifier: GPL-2.0-only > -#include <linux/module.h> > +#include <linux/init.h> > #include <linux/scatterlist.h> > #include <linux/mempool.h> > #include <linux/slab.h> > @@ -177,16 +177,4 @@ static __init int sg_pool_init(void) > return -ENOMEM; > } > > -static __exit void sg_pool_exit(void) > -{ > - int i; > - > - for (i = 0; i < SG_MEMPOOL_NR; i++) { > - struct sg_pool *sgp = sg_pools + i; > - mempool_destroy(sgp->pool); > - kmem_cache_destroy(sgp->slab); > - } > -} > - > -module_init(sg_pool_init); > -module_exit(sg_pool_exit); > +subsys_initcall(sg_pool_init);
On Fri, Sep 23, 2022 at 8:40 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > > sg_alloc_table_chained() is called by several drivers, but if it is > called before sg_pool_init(), it results in a NULL pointer dereference > in sg_pool_alloc(). > > Since commit 9b1d6c895002 ("lib: scatterlist: move SG pool code from > SCSI driver to lib/sg_pool.c"), we rely on module_init(sg_pool_init) > is invoked before other module_init calls but this assumption is > fragile. > > I slightly changed the link order while Kbuild refactoring Kbuild, A nit. while Kbuild refactoring Kbuild -> while refactoring Kbuild > then uncovered this issue. I should keep the current link order, but > depending on a specific call order among module_init is so fragine. fragine -> fragile. > We usually define the init order by specifying *_initcall correctly, > or delay the driver probing by returning -EPROBE_DEFER. > > Change module_initcall() to subsys_initcall(), and also delete the > pointless module_exit() because lib/sg_pool.c is always compiled as > built-in. (CONFIG_SG_POOL is bool) > > Link: https://lore.kernel.org/all/20220921043946.GA1355561@roeck-us.net/ > Link: https://lore.kernel.org/all/8e70837d-d859-dfb2-bf7f-83f8b31467bc@samsung.com/ > Fixes: 9b1d6c895002 ("lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c") > Reported-by: Guenter Roeck <linux@roeck-us.net> > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > --- > > I am sending this to DMA subsystem because I did not find > a corresponding one for lib/sg_pool.c > > lib/sg_pool.c | 16 ++-------------- > 1 file changed, 2 insertions(+), 14 deletions(-) > > diff --git a/lib/sg_pool.c b/lib/sg_pool.c > index a0b1a52cd6f7..9bfe60ca3f37 100644 > --- a/lib/sg_pool.c > +++ b/lib/sg_pool.c > @@ -1,5 +1,5 @@ > // SPDX-License-Identifier: GPL-2.0-only > -#include <linux/module.h> > +#include <linux/init.h> > #include <linux/scatterlist.h> > #include <linux/mempool.h> > #include <linux/slab.h> > @@ -177,16 +177,4 @@ static __init int sg_pool_init(void) > return -ENOMEM; > } > > -static __exit void sg_pool_exit(void) > -{ > - int i; > - > - for (i = 0; i < SG_MEMPOOL_NR; i++) { > - struct sg_pool *sgp = sg_pools + i; > - mempool_destroy(sgp->pool); > - kmem_cache_destroy(sgp->slab); > - } > -} > - > -module_init(sg_pool_init); > -module_exit(sg_pool_exit); > +subsys_initcall(sg_pool_init); > -- > 2.34.1 > -- Best Regards Masahiro Yamada
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