kasan detects access beyond the end of the xibm->bitmap allocation: BUG: KASAN: slab-out-of-bounds in _find_first_zero_bit+0x40/0x140 Read of size 8 at addr c00000001d1d0118 by task swapper/0/1 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-rc2-00001-g90df023b36dd #28 Call Trace: [c00000001d98f770] [c0000000012baab8] dump_stack_lvl+0xac/0x108 (unreliable) [c00000001d98f7b0] [c00000000068faac] print_report+0x37c/0x710 [c00000001d98f880] [c0000000006902c0] kasan_report+0x110/0x354 [c00000001d98f950] [c000000000692324] __asan_load8+0xa4/0xe0 [c00000001d98f970] [c0000000011c6ed0] _find_first_zero_bit+0x40/0x140 [c00000001d98f9b0] [c0000000000dbfbc] xive_spapr_get_ipi+0xcc/0x260 [c00000001d98fa70] [c0000000000d6d28] xive_setup_cpu_ipi+0x1e8/0x450 [c00000001d98fb30] [c000000004032a20] pSeries_smp_probe+0x5c/0x118 [c00000001d98fb60] [c000000004018b44] smp_prepare_cpus+0x944/0x9ac [c00000001d98fc90] [c000000004009f9c] kernel_init_freeable+0x2d4/0x640 [c00000001d98fd90] [c0000000000131e8] kernel_init+0x28/0x1d0 [c00000001d98fe10] [c00000000000cd54] ret_from_kernel_thread+0x5c/0x64 Allocated by task 0: kasan_save_stack+0x34/0x70 __kasan_kmalloc+0xb4/0xf0 __kmalloc+0x268/0x540 xive_spapr_init+0x4d0/0x77c pseries_init_irq+0x40/0x27c init_IRQ+0x44/0x84 start_kernel+0x2a4/0x538 start_here_common+0x1c/0x20 The buggy address belongs to the object at c00000001d1d0118 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 0 bytes inside of 8-byte region [c00000001d1d0118, c00000001d1d0120) The buggy address belongs to the physical page: page:c00c000000074740 refcount:1 mapcount:0 mapping:0000000000000000 index:0xc00000001d1d0558 pfn:0x1d1d flags: 0x7ffff000000200(slab|node=0|zone=0|lastcpupid=0x7ffff) raw: 007ffff000000200 c00000001d0003c8 c00000001d0003c8 c00000001d010480 raw: c00000001d1d0558 0000000001e1000a 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: c00000001d1d0000: fc 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc c00000001d1d0080: fc fc 00 fc fc fc fc fc fc fc fc fc fc fc fc fc >c00000001d1d0100: fc fc fc 02 fc fc fc fc fc fc fc fc fc fc fc fc ^ c00000001d1d0180: fc fc fc fc 04 fc fc fc fc fc fc fc fc fc fc fc c00000001d1d0200: fc fc fc fc fc 04 fc fc fc fc fc fc fc fc fc fc This happens because the allocation uses the wrong unit (bits) when it should pass (BITS_TO_LONGS(count) * sizeof(long)) or equivalent. With small numbers of bits, the allocated object can be smaller than sizeof(long), which results in invalid accesses. Use bitmap_zalloc() to allocate and initialize the irq bitmap, paired with bitmap_free() for consistency.
Unified · Split
| @@ -15,6 +15,7 @@ · 14 unmodified lines | ||
| 15 | 15 | #include <linux/of_fdt.h> |
| 16 | 16 | #include <linux/slab.h> |
| 17 | 17 | #include <linux/spinlock.h> |
| 18 | +#include <linux/bitmap.h> | |
| 18 | 19 | #include <linux/cpumask.h> |
| 19 | 20 | #include <linux/mm.h> |
| 20 | 21 | #include <linux/delay.h> |
| @@ -57,7 +58,7 @@ static int __init xive_irq_bitmap_add(int base, int count) · 36 unmodified lines | ||
| 57 | 58 | spin_lock_init(&xibm->lock); |
| 58 | 59 | xibm->base = base; |
| 59 | 60 | xibm->count = count; |
| 60 | − xibm->bitmap = kzalloc(xibm->count, GFP_KERNEL); | |
| 61 | + xibm->bitmap = bitmap_zalloc(xibm->count, GFP_KERNEL); | |
| 61 | 62 | if (!xibm->bitmap) { |
| 62 | 63 | kfree(xibm); |
| 63 | 64 | return -ENOMEM; |
| @@ -75,7 +76,7 @@ static void xive_irq_bitmap_remove_all(void) · 11 unmodified lines | ||
| 75 | 76 | |
| 76 | 77 | list_for_each_entry_safe(xibm, tmp, &xive_irq_bitmaps, list) { |
| 77 | 78 | list_del(&xibm->list); |
| 78 | − kfree(xibm->bitmap); | |
| 79 | + bitmap_free(xibm->bitmap); | |
| 79 | 80 | kfree(xibm); |
| 80 | 81 | } |
| 81 | 82 | } |