[Bug 216073] [s390x] kernel BUG at mm/usercopy.c:101! usercopy: Kernel memory exposure attempt detected from vmalloc 'n o area' (offset 0, size 1)!

bugzilla-daemon
2022-06-12T11:59:25Z

--- Comment #11 from willy@infradead.org ---
On Sun, Jun 12, 2022 at 12:42:30PM +0800, Zorro Lang wrote:
> Looks likt it's not a s390x specific bug, I just hit this issue once (not
> 100%
> reproducible) on aarch64 with linux v5.19.0-rc1+ [1]. So back to cc linux-mm
> to get more review.
>
> [1]
> [ 980.200947] usercopy: Kernel memory exposure attempt detected from vmalloc
> 'no area' (offset 0, size 1)!

if (is_vmalloc_addr(ptr)) {
struct vm_struct *area = find_vm_area(ptr);
if (!area) {
usercopy_abort("vmalloc", "no area", to_user, 0, n);

Oh. Looks like XFS uses vm_map_ram() and vm_map_ram() doesn't allocate
a vm_struct.

Ulad, how does this look to you?

diff --git a/mm/usercopy.c b/mm/usercopy.c
index baeacc735b83..6bc2a1407c59 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -173,7 +173,7 @@ static inline void check_heap_object(const void *ptr,
unsigned long n,
}

if (is_vmalloc_addr(ptr)) {
- struct vm_struct *area = find_vm_area(ptr);
+ struct vmap_area *area = find_vmap_area((unsigned long)ptr);
unsigned long offset;

if (!area) {
@@ -181,8 +181,9 @@ static inline void check_heap_object(const void *ptr,
unsigned long n,
return;
}

- offset = ptr - area->addr;
- if (offset + n > get_vm_area_size(area))
+ /* XXX: We should also abort for free vmap_areas */
+ offset = (unsigned long)ptr - area->va_start;
+ if (offset + n >= area->va_end)
usercopy_abort("vmalloc", NULL, to_user, offset, n);
return;
}
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 07db42455dd4..effd1ff6a4b4 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1798,7 +1798,7 @@ static void free_unmap_vmap_area(struct vmap_area *va)
free_vmap_area_noflush(va);
}

-static struct vmap_area *find_vmap_area(unsigned long addr)
+struct vmap_area *find_vmap_area(unsigned long addr)
{
struct vmap_area *va;

> [ 980.200968] ------------[ cut here ]------------
> [ 980.200969] kernel BUG at mm/usercopy.c:101!
> [ 980.201081] Internal error: Oops - BUG: 0 [#1] SMP
> [ 980.224192] Modules linked in: rfkill arm_spe_pmu mlx5_ib ast
> drm_vram_helper drm_ttm_helper ttm ib_uverbs acpi_ipmi drm_kms_helper
> ipmi_ssif fb_sys_fops syscopyarea sysfillrect ib_core sysimgblt arm_cmn
> arm_dmc620_pmu arm_dsu_pmu cppc_cpufreq sunrpc vfat fat drm fuse xfs
> libcrc32c mlx5_core crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce
> sbsa_gwdt nvme igb mlxfw nvme_core tls i2c_algo_bit psample pci_hyperv_intf
> i2c_designware_platform i2c_designware_core xgene_hwmon ipmi_devintf
> ipmi_msghandler
> [ 980.268449] CPU: 42 PID: 121940 Comm: rm Kdump: loaded Not tainted
> 5.19.0-rc1+ #1
> [ 980.275921] Hardware name: GIGABYTE R272-P30-JG/MP32-AR0-JG, BIOS F16f
> (SCP: 1.06.20210615) 07/01/2021
> [ 980.285214] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
> BTYPE=--)
> [ 980.292165] pc : usercopy_abort+0x78/0x7c
> [ 980.296167] lr : usercopy_abort+0x78/0x7c
> [ 980.300166] sp : ffff80002b007730
> [ 980.303469] x29: ffff80002b007740 x28: ffff80002b007cc0 x27:
> ffffdc5683ecc880
> [ 980.310595] x26: 1ffff00005600f9b x25: ffffdc5681c90000 x24:
> ffff80002b007cdc
> [ 980.317722] x23: ffff800041a0004a x22: 0000000000000001 x21:
> 0000000000000001
> [ 980.324848] x20: 0000000000000000 x19: ffff800041a00049 x18:
> 0000000000000000
> [ 980.331974] x17: 2720636f6c6c616d x16: 76206d6f72662064 x15:
> 6574636574656420
> [ 980.339101] x14: 74706d6574746120 x13: 21293120657a6973 x12:
> ffff6106cbc4c03f
> [ 980.346227] x11: 1fffe106cbc4c03e x10: ffff6106cbc4c03e x9 :
> ffffdc5681f36e30
> [ 980.353353] x8 : ffff08365e2601f7 x7 : 0000000000000001 x6 :
> ffff6106cbc4c03e
> [ 980.360480] x5 : ffff08365e2601f0 x4 : 1fffe10044b11801 x3 :
> 0000000000000000
> [ 980.367606] x2 : 0000000000000000 x1 : ffff08022588c000 x0 :
> 000000000000005c
> [ 980.374733] Call trace:
> [ 980.377167] usercopy_abort+0x78/0x7c
> [ 980.380819] check_heap_object+0x3dc/0x3e0
> [ 980.384907] __check_object_size.part.0+0x6c/0x1f0
> [ 980.389688] __check_object_size+0x24/0x30
> [ 980.393774] filldir64+0x548/0x84c
> [ 980.397165] xfs_dir2_block_getdents+0x404/0x960 [xfs]
> [ 980.402437] xfs_readdir+0x3c4/0x4b0 [xfs]
> [ 980.406652] xfs_file_readdir+0x6c/0xa0 [xfs]
> [ 980.411127] iterate_dir+0x3a4/0x500