The quilt patch titled
Subject: mm/vmalloc: fix the unchecked dereference warning in vread_iter()
has been removed from the -mm tree. Its filename was
mm-vmalloc-fix-the-unchecked-dereference-warning-in-vread_iter.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Baoquan He <bhe@xxxxxxxxxx>
Subject: mm/vmalloc: fix the unchecked dereference warning in vread_iter()
Date: Wed, 18 Oct 2023 22:50:14 +0800
LKP reported smatch warning as below:
===================
smatch warnings:
mm/vmalloc.c:3689 vread_iter() error: we previously assumed 'vm' could be null (see line 3667)
......
06c8994626d1b7 @3667 size = vm ? get_vm_area_size(vm) : va_size(va);
......
06c8994626d1b7 @3689 else if (!(vm->flags & VM_IOREMAP))
^^^^^^^^^
Unchecked dereference
=====================
This is not a runtime bug because the possible null 'vm' in the
pointed place could only happen when flags == VMAP_BLOCK. However, the
case 'flags == VMAP_BLOCK' should never happen and has been detected
with WARN_ON. Please check vm_map_ram() implementation and the earlier
checking in vread_iter() at below:
~~~~~~~~~~~~~~~~~~~~~~~~~~
/*
* VMAP_BLOCK indicates a sub-type of vm_map_ram area, need
* be set together with VMAP_RAM.
*/
WARN_ON(flags == VMAP_BLOCK);
if (!vm && !flags)
continue;
~~~~~~~~~~~~~~~~~~~~~~~~~~
So add checking on whether 'vm' could be null when dereferencing it in
vread_iter(). This mutes smatch complaint.
Link: https://lkml.kernel.org/r/ZTCURc8ZQE+KrTvS@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/ZS/2k6DIMd0tZRgK@MiWiFi-R3L-srv
Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Closes: https://lore.kernel.org/r/202310171600.WCrsOwFj-lkp@xxxxxxxxx/
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Philip Li <philip.li@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/vmalloc.c~mm-vmalloc-fix-the-unchecked-dereference-warning-in-vread_iter
+++ a/mm/vmalloc.c
@@ -3809,7 +3809,7 @@ long vread_iter(struct iov_iter *iter, c
if (flags & VMAP_RAM)
copied = vmap_ram_vread_iter(iter, addr, n, flags);
- else if (!(vm->flags & VM_IOREMAP))
+ else if (!(vm && (vm->flags & VM_IOREMAP)))
copied = aligned_vread_iter(iter, addr, n);
else /* IOREMAP area is treated as memory hole */
copied = zero_iter(iter, n);
_
Patches currently in -mm which might be from bhe@xxxxxxxxxx are
