| Message ID | 1434530713-81591-2-git-send-email-shengyong1@huawei.com |
|---|---|
| State | Accepted |
| Commit | ec7478fa173f65e5ee5fd2ba42c59ca3e700027b |
| Headers | show |
Am 17.06.2015 um 10:45 schrieb Sheng Yong: > If allocating ns->nand_pages_slab fails, do not try to destroy it when > cleaning up nandsim resources. > > Signed-off-by: Sheng Yong <shengyong1@huawei.com> > --- > drivers/mtd/nand/nandsim.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c > index cb38f3d..33e4064 100644 > --- a/drivers/mtd/nand/nandsim.c > +++ b/drivers/mtd/nand/nandsim.c > @@ -646,7 +646,8 @@ static void free_device(struct nandsim *ns) > kmem_cache_free(ns->nand_pages_slab, > ns->pages[i].byte); > } > - kmem_cache_destroy(ns->nand_pages_slab); > + if (ns->nand_pages_slab) > + kmem_cache_destroy(ns->nand_pages_slab); It is perfectly fine to free a NULL pointer. Thanks, //richard
Am 17.06.2015 um 10:48 schrieb Richard Weinberger: > Am 17.06.2015 um 10:45 schrieb Sheng Yong: >> If allocating ns->nand_pages_slab fails, do not try to destroy it when >> cleaning up nandsim resources. >> >> Signed-off-by: Sheng Yong <shengyong1@huawei.com> >> --- >> drivers/mtd/nand/nandsim.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c >> index cb38f3d..33e4064 100644 >> --- a/drivers/mtd/nand/nandsim.c >> +++ b/drivers/mtd/nand/nandsim.c >> @@ -646,7 +646,8 @@ static void free_device(struct nandsim *ns) >> kmem_cache_free(ns->nand_pages_slab, >> ns->pages[i].byte); >> } >> - kmem_cache_destroy(ns->nand_pages_slab); >> + if (ns->nand_pages_slab) >> + kmem_cache_destroy(ns->nand_pages_slab); > > It is perfectly fine to free a NULL pointer. Ignore that. /me needs more coffee. ;) Thanks, //richard
On 6/17/2015 4:48 PM, Richard Weinberger wrote: > Am 17.06.2015 um 10:45 schrieb Sheng Yong: >> If allocating ns->nand_pages_slab fails, do not try to destroy it when >> cleaning up nandsim resources. >> >> Signed-off-by: Sheng Yong <shengyong1@huawei.com> >> --- >> drivers/mtd/nand/nandsim.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c >> index cb38f3d..33e4064 100644 >> --- a/drivers/mtd/nand/nandsim.c >> +++ b/drivers/mtd/nand/nandsim.c >> @@ -646,7 +646,8 @@ static void free_device(struct nandsim *ns) >> kmem_cache_free(ns->nand_pages_slab, >> ns->pages[i].byte); >> } >> - kmem_cache_destroy(ns->nand_pages_slab); >> + if (ns->nand_pages_slab) >> + kmem_cache_destroy(ns->nand_pages_slab); > > It is perfectly fine to free a NULL pointer. OK, then maybe the double free is not a serious problem, besides we just get a message "Trying to vfree() nonexistent vm area" or the like. But kmem_cache_destroy() will access ns->nand_pages_slab, and ns->nand_pages_slab is NULL. This will crash the kernel. :) thanks, Sheng > > Thanks, > //richard > > . >
Am 17.06.2015 um 11:03 schrieb Sheng Yong: > > > On 6/17/2015 4:48 PM, Richard Weinberger wrote: >> Am 17.06.2015 um 10:45 schrieb Sheng Yong: >>> If allocating ns->nand_pages_slab fails, do not try to destroy it when >>> cleaning up nandsim resources. >>> >>> Signed-off-by: Sheng Yong <shengyong1@huawei.com> >>> --- >>> drivers/mtd/nand/nandsim.c | 3 ++- >>> 1 file changed, 2 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c >>> index cb38f3d..33e4064 100644 >>> --- a/drivers/mtd/nand/nandsim.c >>> +++ b/drivers/mtd/nand/nandsim.c >>> @@ -646,7 +646,8 @@ static void free_device(struct nandsim *ns) >>> kmem_cache_free(ns->nand_pages_slab, >>> ns->pages[i].byte); >>> } >>> - kmem_cache_destroy(ns->nand_pages_slab); >>> + if (ns->nand_pages_slab) >>> + kmem_cache_destroy(ns->nand_pages_slab); >> >> It is perfectly fine to free a NULL pointer. > OK, then maybe the double free is not a serious problem, besides we just > get a message "Trying to vfree() nonexistent vm area" or the like. But > kmem_cache_destroy() will access ns->nand_pages_slab, and ns->nand_pages_slab > is NULL. This will crash the kernel. :) Please see my other may, I was wrong. :) Thanks, //richard
diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c index cb38f3d..33e4064 100644 --- a/drivers/mtd/nand/nandsim.c +++ b/drivers/mtd/nand/nandsim.c @@ -646,7 +646,8 @@ static void free_device(struct nandsim *ns) kmem_cache_free(ns->nand_pages_slab, ns->pages[i].byte); } - kmem_cache_destroy(ns->nand_pages_slab); + if (ns->nand_pages_slab) + kmem_cache_destroy(ns->nand_pages_slab); vfree(ns->pages); } }
If allocating ns->nand_pages_slab fails, do not try to destroy it when cleaning up nandsim resources. Signed-off-by: Sheng Yong <shengyong1@huawei.com> --- drivers/mtd/nand/nandsim.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)