From: Patrick Wang patrick.wang.shcn@gmail.com Subject: mm: kmemleak: take a full lowmem check in kmemleak_*_phys()

The kmemleak_*_phys() apis do not check the address for lowmem's min boundary, while the caller may pass an address below lowmem, which will trigger an oops:

# echo scan > /sys/kernel/debug/kmemleak [ 54.888353] Unable to handle kernel paging request at virtual address ff5fffffffe00000 [ 54.888932] Oops [#1] [ 54.889102] Modules linked in: [ 54.889326] CPU: 2 PID: 134 Comm: bash Not tainted 5.18.0-rc1-next-20220407 #33 [ 54.889620] Hardware name: riscv-virtio,qemu (DT) [ 54.889901] epc : scan_block+0x74/0x15c [ 54.890215] ra : scan_block+0x72/0x15c [ 54.890390] epc : ffffffff801e5806 ra : ffffffff801e5804 sp : ff200000104abc30 [ 54.890607] gp : ffffffff815cd4e8 tp : ff60000004cfa340 t0 : 0000000000000200 [ 54.890835] t1 : 00aaaaaac23954cc t2 : 00000000000003ff s0 : ff200000104abc90 [ 54.891024] s1 : ffffffff81b0ff28 a0 : 0000000000000000 a1 : ff5fffffffe01000 [ 54.891201] a2 : ffffffff81b0ff28 a3 : 0000000000000002 a4 : 0000000000000001 [ 54.891377] a5 : 0000000000000000 a6 : ff200000104abd7c a7 : 0000000000000005 [ 54.891552] s2 : ff5fffffffe00ff9 s3 : ffffffff815cd998 s4 : ffffffff815d0e90 [ 54.891727] s5 : ffffffff81b0ff28 s6 : 0000000000000020 s7 : ffffffff815d0eb0 [ 54.891903] s8 : ffffffffffffffff s9 : ff5fffffffe00000 s10: ff5fffffffe01000 [ 54.892078] s11: 0000000000000022 t3 : 00ffffffaa17db4c t4 : 000000000000000f [ 54.892271] t5 : 0000000000000001 t6 : 0000000000000000 [ 54.892408] status: 0000000000000100 badaddr: ff5fffffffe00000 cause: 000000000000000d [ 54.892643] [<ffffffff801e5a1c>] scan_gray_list+0x12e/0x1a6 [ 54.892824] [<ffffffff801e5d3e>] kmemleak_scan+0x2aa/0x57e [ 54.892961] [<ffffffff801e633c>] kmemleak_write+0x32a/0x40c [ 54.893096] [<ffffffff803915ac>] full_proxy_write+0x56/0x82 [ 54.893235] [<ffffffff801ef456>] vfs_write+0xa6/0x2a6 [ 54.893362] [<ffffffff801ef880>] ksys_write+0x6c/0xe2 [ 54.893487] [<ffffffff801ef918>] sys_write+0x22/0x2a [ 54.893609] [<ffffffff8000397c>] ret_from_syscall+0x0/0x2 [ 54.894183] ---[ end trace 0000000000000000 ]---

The callers may not quite know the actual address they pass(e.g. from devicetree). So the kmemleak_*_phys() apis should guarantee the address they finally use is in lowmem range, so check the address for lowmem's min boundary.

Link: https://lkml.kernel.org/r/20220413122925.33856-1-patrick.wang.shcn@gmail.com Signed-off-by: Patrick Wang patrick.wang.shcn@gmail.com Acked-by: Catalin Marinas catalin.marinas@arm.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/kmemleak.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/kmemleak.c~mm-kmemleak-take-a-full-lowmem-check-in-kmemleak__phys +++ a/mm/kmemleak.c @@ -1132,7 +1132,7 @@ EXPORT_SYMBOL(kmemleak_no_scan); void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count, gfp_t gfp) { - if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn) + if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) kmemleak_alloc(__va(phys), size, min_count, gfp); } EXPORT_SYMBOL(kmemleak_alloc_phys); @@ -1146,7 +1146,7 @@ EXPORT_SYMBOL(kmemleak_alloc_phys); */ void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size) { - if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn) + if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) kmemleak_free_part(__va(phys), size); } EXPORT_SYMBOL(kmemleak_free_part_phys); @@ -1158,7 +1158,7 @@ EXPORT_SYMBOL(kmemleak_free_part_phys); */ void __ref kmemleak_not_leak_phys(phys_addr_t phys) { - if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn) + if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) kmemleak_not_leak(__va(phys)); } EXPORT_SYMBOL(kmemleak_not_leak_phys); @@ -1170,7 +1170,7 @@ EXPORT_SYMBOL(kmemleak_not_leak_phys); */ void __ref kmemleak_ignore_phys(phys_addr_t phys) { - if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn) + if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) kmemleak_ignore(__va(phys)); } EXPORT_SYMBOL(kmemleak_ignore_phys); _