[PATCH 1/2] powerpc/powernv/memtrace: Fix out of bounds issue in memtrace mmap

[PATCH 1/2] powerpc/powernv/memtrace: Fix out of bounds issue in memtrace mmap

[Madhavan Srinivasan]

From: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>

memtrace mmap issue has an out of bounds issue. This patch fixes the by
checking that the requested mapping region size should stay within the
allocated region size.

Reported-by: Jonathan Greental <yonatan02greental@gmail.com>
Fixes: 08a022ad3dfa ("powerpc/powernv/memtrace: Allow mmaping trace buffers")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
---
 arch/powerpc/platforms/powernv/memtrace.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c
index 4ac9808e55a4..2ea30b343354 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -48,11 +48,15 @@ static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
 static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct memtrace_entry *ent = filp->private_data;
+	unsigned long ent_nrpages = ent->size >> PAGE_SHIFT;
+	unsigned long vma_nrpages = vma_pages(vma);
 
-	if (ent->size < vma->vm_end - vma->vm_start)
+	/* The requested page offset should be within object's page count */
+	if (vma->vm_pgoff >= ent_nrpages)
 		return -EINVAL;
 
-	if (vma->vm_pgoff << PAGE_SHIFT >= ent->size)
+	/* The requested mapping range should remain within the bounds */
+	if (vma_nrpages > ent_nrpages - vma->vm_pgoff)
 		return -EINVAL;
 
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-- 
2.46.0

[PATCH 2/2] powerpc/vas: Return -EINVAL if the offset is non-zero in mmap()

[Madhavan Srinivasan]

The user space calls mmap() to map VAS window paste address
and the kernel returns the complete mapped page for each
window. So return -EINVAL if non-zero is passed for offset
parameter to mmap().

See Documentation/arch/powerpc/vas-api.rst for mmap()
restrictions.

Co-developed-by: Jonathan Greental <yonatan02greental@gmail.com>
Signed-off-by: Jonathan Greental <yonatan02greental@gmail.com>
Reported-by: Jonathan Greental <yonatan02greental@gmail.com>
Fixes: dda44eb29c23 ("powerpc/vas: Add VAS user space API")
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
---
 arch/powerpc/platforms/book3s/vas-api.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
index 0b6365d85d11..dc6f75d3ac6e 100644
--- a/arch/powerpc/platforms/book3s/vas-api.c
+++ b/arch/powerpc/platforms/book3s/vas-api.c
@@ -521,6 +521,15 @@ static int coproc_mmap(struct file *fp, struct vm_area_struct *vma)
 		return -EINVAL;
 	}
 
+	/*
+	 * Map complete page to the paste address. So the user
+	 * space should pass 0ULL to the offset parameter.
+	 */
+	if (vma->vm_pgoff) {
+		pr_debug("Page offset unsupported to map paste address\n");
+		return -EINVAL;
+	}
+
 	/* Ensure instance has an open send window */
 	if (!txwin) {
 		pr_err("No send window open?\n");
-- 
2.46.0