4.9-stable review patch. If anyone has any objections, please let me know.
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From: Davidlohr Bueso dave@stgolabs.net
[ Upstream commit 69c907022a7d9325cdc5c9dd064571e445df9a47 ]
At the point of sysfs callback, the call to gup is done without mmap_sem (or any lock for that matter). This is racy. As such, use the get_user_pages_fast() alternative and safely avoid taking the lock, if possible.
Signed-off-by: Davidlohr Bueso dbueso@suse.de Signed-off-by: Tony Luck tony.luck@intel.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/ia64/kernel/err_inject.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/ia64/kernel/err_inject.c +++ b/arch/ia64/kernel/err_inject.c @@ -142,7 +142,7 @@ store_virtual_to_phys(struct device *dev u64 virt_addr=simple_strtoull(buf, NULL, 16); int ret;
- ret = get_user_pages(virt_addr, 1, FOLL_WRITE, NULL, NULL); + ret = get_user_pages_fast(virt_addr, 1, FOLL_WRITE, NULL); if (ret<=0) { #ifdef ERR_INJ_DEBUG printk("Virtual address %lx is not existing.\n",virt_addr);