Inserting the following kernel module:
<snip>
static int simple_test_init(void)
{
size_t i, j;
void *address;
for (i = 0 * MB; i< 60 * MB; i += 1 * MB) {
for (j = i; j< i + 1 * MB; j += KB) {
address = vmalloc(j);
vfree(address);
}
}
return 0;
}
</snip>
triggers BUG at mm/vmalloc.c:310 on a x86 machine:
[ 95.218283] Kernel BUG at c1126cdb [verbose debug info unavailable]
[ 95.218306] invalid opcode: 0000 [#1] SMP
[ 95.218324] Modules linked in: lkma_test(OF+)<snip lots of not tainted modules>
[ 95.218559] Pid: 2419, comm: insmod Tainted: GF O 3.9.0+ #57 Hewlett-Packard HP Compaq 8200 Elite CMT PC/1494
[ 95.218597] EIP: 0060:[<c1126cdb>] EFLAGS: 00010207 CPU: 3
[ 95.218617] EIP is at __insert_vmap_area+0xfb/0x100
[ 95.218635] EAX: f85dc000 EBX: ef05cac0 ECX: f7be08c4 EDX: 00000007
[ 95.218657] ESI: f2ed044c EDI: c1a220b8 EBP: f027bd34 ESP: f027bd14
[ 95.218680] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[ 95.218699] CR0: 80050033 CR2: b5995118 CR3: 30364000 CR4: 000407f0
[ 95.218721] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[ 95.218743] DR6: ffff0ff0 DR7: 00000400
[ 95.218758] Process insmod (pid: 2419, ti=f027a000 task=efe64010 task.ti=f027a000)
[ 95.218784] Stack:
[ 95.218792] c177b964 fecfb000 f85e2000 00000000 f85dc000 ffbfe000 f02da1c0 0007f000
[ 95.218829] f027bd7c c112802d c177b9b0 fecfb000 01305000 ffbfe000 00000001 ef05cac0
[ 95.218866] 00000000 00000000 f83fe000 01304fff f83fe000 ffffffff 01305000 ef05c500
[ 95.218903] Call Trace:
[ 95.218915] [<f85e2000>] ? 0xf85e1fff
[ 95.218930] [<f85dc000>] ? 0xf85dbfff
[ 95.218945] [<c112802d>] alloc_vmap_area.isra.16+0x1bd/0x2f0
[ 95.218967] [<c112867f>] __get_vm_area_node.isra.17+0x8f/0x130
[ 95.218988] [<c1128d77>] __vmalloc_node_range+0x57/0x200
[ 95.219009] [<f85f3075>] ? lkma_test_init+0x45/0x70 [lkma_test]
[ 95.219031] [<c1128f82>] __vmalloc_node+0x62/0x70
[ 95.219049] [<f85f3075>] ? lkma_test_init+0x45/0x70 [lkma_test]
[ 95.219071] [<c1129058>] vmalloc+0x38/0x40
[ 95.219087] [<f85f3075>] ? lkma_test_init+0x45/0x70 [lkma_test]
[ 95.219109] [<f85f3075>] lkma_test_init+0x45/0x70 [lkma_test]
[ 95.219131] [<f85f3030>] ? kzalloc+0x10/0x10 [lkma_test]
[ 95.219151] [<c1001222>] do_one_initcall+0x112/0x160
[ 95.219171] [<c15ca3cf>] ? set_section_ro_nx+0x54/0x59
[ 95.219190] [<c1099b69>] load_module+0x1d79/0x2660
[ 95.219209] [<c114721d>] ? create_object+0x19d/0x280
[ 95.219230] [<c109a4c8>] sys_init_module+0x78/0xb0
[ 95.219250] [<c15d9801>] sysenter_do_call+0x12/0x22
[ 95.219268] Code: 39 03 73 0c 8b 3f 89 f0 83 c7 08 e9 3d ff ff ff 8b 46 f4 39 43 04 76 13 8b 3f 89 f0 83 c7 04 e9 29 ff ff ff e8 fb 1b 4a 00 eb ab<0f> 0b 8d 76 00 55 89 e5 56 53 66 66 66 66 90 83 60 0c df 89 c6
[ 95.219415] EIP: [<c1126cdb>] __insert_vmap_area+0xfb/0x100 SS:ESP 0068:f027bd14
[ 95.228313] ---[ end trace e0a1efb2acb97c98 ]---
A printk placed in __insert_vmap_area will show:
[ 95.218256] va->va_start=0xfecfb000 tmp_va->va_end=0xf85e2000 va->va_end=0 tmp_va->va_start=0xf85dc000
and another one, before sum operation in alloc_vmap_area:
[ 95.218204] addr = 0xfecfb000 size = 19943424 vend = 0xffbfe000
If after addition the result is smaller than one of the arguments,
then an overflow occurred. In our case there is an obvious overflow.
Signed-off-by: Ghennadi Procopciuc <unix140@xxxxxxxxx>
Cc: Daniel Baluta<dbaluta@xxxxxxxxxxx>
---
Don't know if this is the right solution, but the bug happens for me in
3.10-rc6 and 3.9.
---
mm/vmalloc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 0f751f2..6ea525c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -421,12 +421,13 @@ nocache:
}
found:
- if (addr + size > vend)
+ va->va_end = addr + size;
+ if (va->va_end < addr || va->va_end < size || va->va_end > vend)
goto overflow;
va->va_start = addr;
- va->va_end = addr + size;
va->flags = 0;
+
__insert_vmap_area(va);
free_vmap_cache = &va->rb_node;
spin_unlock(&vmap_area_lock);
--
1.8.1.2
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