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authorBaoquan He <bhe@redhat.com>2023-10-18 22:50:14 +0800
committerAndrew Morton <akpm@linux-foundation.org>2023-11-01 12:38:35 -0700
commitca6c2ce1b481996ae5b16e4589d3c0dd61899fa8 (patch)
treea479e803972a465a2fca68e6c3ab4ef36018cd5f
parentcb61dad80fdc6a8f01b101e823a9335cd6d61071 (diff)
mm/vmalloc: fix the unchecked dereference warning in vread_iter()
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@redhat.com> Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <dan.carpenter@linaro.org> Closes: https://lore.kernel.org/r/202310171600.WCrsOwFj-lkp@intel.com/ Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Philip Li <philip.li@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--mm/vmalloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a3fedb3ee0db..d12a17fc0c17 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3809,7 +3809,7 @@ long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
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);