kevin/linux
1
Fork 0
Code

Revert "mm,memblock: reset memblock.reserved to system init state to prevent UAF"

Browse Source 
This reverts commit 9e46e4dcd9.

kbuild reports a warning in memblock_remove_region() because of a false
positive caused by partial reset of the memblock state.

Doing the full reset will remove the false positives, but will allow
late use of memblock_free() to go unnoticed, so it is better to revert
the offending commit.

   WARNING: CPU: 0 PID: 1 at mm/memblock.c:352 memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminator 1))
   Modules linked in:
   CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc3-00001-g9e46e4dcd9d6 #2
   RIP: 0010:memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminator 1))
   Call Trace:
     memblock_discard (kbuild/src/x86_64/mm/memblock.c:383)
     page_alloc_init_late (kbuild/src/x86_64/include/linux/find.h:208 kbuild/src/x86_64/include/linux/nodemask.h:266 kbuild/src/x86_64/mm/mm_init.c:2405)
     kernel_init_freeable (kbuild/src/x86_64/init/main.c:1325 kbuild/src/x86_64/init/main.c:1546)
     kernel_init (kbuild/src/x86_64/init/main.c:1439)
     ret_from_fork (kbuild/src/x86_64/arch/x86/kernel/process.c:145)
     ret_from_fork_asm (kbuild/src/x86_64/arch/x86/entry/entry_64.S:298)

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202307271656.447aa17e-oliver.sang@intel.com
Signed-off-by: "Mike Rapoport (IBM)" <rppt@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Rapoport (IBM) 2023-07-28 13:55:12 +03:00 committed by Linus Torvalds
parent 6c21e066f9
commit c442a957b2
1 changed files with 0 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
mm/memblock.c
View File

@ -374,10 +374,6 @@ void __init memblock_discard(void)
kfree(memblock.reserved.regions); kfree(memblock.reserved.regions);
else else
memblock_free_late(addr, size); memblock_free_late(addr, size);
/* Reset to prevent UAF from stray frees. */
memblock.reserved.regions = memblock_reserved_init_regions;
memblock.reserved.cnt = 1;
memblock_remove_region(&memblock.reserved, 0);
} }
if (memblock.memory.regions != memblock_memory_init_regions) { if (memblock.memory.regions != memblock_memory_init_regions) {