From: Baoquan He bhe@redhat.com
mainline inclusion from mainline-v6.7-rc1 commit ca6c2ce1b481996ae5b16e4589d3c0dd61899fa8 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CHG1 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 (cherry picked from commit ca6c2ce1b481996ae5b16e4589d3c0dd61899fa8) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: ZhangPeng zhangpeng362@huawei.com --- mm/vmalloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 31761425d7a8..8210afa4e888 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3814,7 +3814,7 @@ 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);