IB/hfi1: Remove overly conservative VM_EXEC flag check

mjruhl · jgunthorpe · commit 7709b0dc265f · 2019-01-21T14:20:08.000-07:00
Applications that use the stack for execution purposes cause userspace PSM jobs to fail during mmap(). Both Fortran (non-standard format parsing) and C (callback functions located in the stack) applications can be written such that stack execution is required. The linker notes this via the gnu_stack ELF flag. This causes READ_IMPLIES_EXEC to be set which forces all PROT_READ mmaps to have PROT_EXEC for the process. Checking for VM_EXEC bit and failing the request with EPERM is overly conservative and will break any PSM application using executable stacks. Cc: <stable@vger.kernel.org> #v4.14+ Fixes: 1222026 ("IB/hfi: Protect against writable mmap") Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -488,7 +488,7 @@ static int hfi1_file_mmap(struct file *fp, struct vm_area_struct *vma)
 		vmf = 1;
 		break;
 	case STATUS:
-		if (flags & (unsigned long)(VM_WRITE | VM_EXEC)) {
+		if (flags & VM_WRITE) {
 			ret = -EPERM;
 			goto done;
 		}

Original file line number	Diff line number	Diff line change
`@@ -488,7 +488,7 @@ static int hfi1_file_mmap(struct file fp, struct vm_area_struct vma)`
`488`	`488`	`vmf = 1;`
`489`	`489`	`break;`
`490`	`490`	`case STATUS:`
`491`		`- if (flags & (unsigned long)(VM_WRITE \| VM_EXEC)) {`
	`491`	`+ if (flags & VM_WRITE) {`
`492`	`492`	`ret = -EPERM;`
`493`	`493`	`goto done;`
`494`	`494`	`}`