| From c6f58d9b362b45c52afebe4342c9137d0dabe47f Mon Sep 17 00:00:00 2001 |
| From: Christoph Lameter <cl@linux.com> |
| Date: Thu, 7 Nov 2013 16:29:15 +0000 |
| Subject: slub: Handle NULL parameter in kmem_cache_flags |
| |
| From: Christoph Lameter <cl@linux.com> |
| |
| commit c6f58d9b362b45c52afebe4342c9137d0dabe47f upstream. |
| |
| Andreas Herrmann writes: |
| |
| When I've used slub_debug kernel option (e.g. |
| "slub_debug=,skbuff_fclone_cache" or similar) on a debug session I've |
| seen a panic like: |
| |
| Highbank #setenv bootargs console=ttyAMA0 root=/dev/sda2 kgdboc.kgdboc=ttyAMA0,115200 slub_debug=,kmalloc-4096 earlyprintk=ttyAMA0 |
| ... |
| Unable to handle kernel NULL pointer dereference at virtual address 00000000 |
| pgd = c0004000 |
| [00000000] *pgd=00000000 |
| Internal error: Oops: 5 [#1] SMP ARM |
| Modules linked in: |
| CPU: 0 PID: 0 Comm: swapper Tainted: G W 3.12.0-00048-gbe408cd #314 |
| task: c0898360 ti: c088a000 task.ti: c088a000 |
| PC is at strncmp+0x1c/0x84 |
| LR is at kmem_cache_flags.isra.46.part.47+0x44/0x60 |
| pc : [<c02c6da0>] lr : [<c0110a3c>] psr: 200001d3 |
| sp : c088bea8 ip : c088beb8 fp : c088beb4 |
| r10: 00000000 r9 : 413fc090 r8 : 00000001 |
| r7 : 00000000 r6 : c2984a08 r5 : c0966e78 r4 : 00000000 |
| r3 : 0000006b r2 : 0000000c r1 : 00000000 r0 : c2984a08 |
| Flags: nzCv IRQs off FIQs off Mode SVC_32 ISA ARM Segment kernel |
| Control: 10c5387d Table: 0000404a DAC: 00000015 |
| Process swapper (pid: 0, stack limit = 0xc088a248) |
| Stack: (0xc088bea8 to 0xc088c000) |
| bea0: c088bed4 c088beb8 c0110a3c c02c6d90 c0966e78 00000040 |
| bec0: ef001f00 00000040 c088bf14 c088bed8 c0112070 c0110a04 00000005 c010fac8 |
| bee0: c088bf5c c088bef0 c010fac8 ef001f00 00000040 00000000 00000040 00000001 |
| bf00: 413fc090 00000000 c088bf34 c088bf18 c0839190 c0112040 00000000 ef001f00 |
| bf20: 00000000 00000000 c088bf54 c088bf38 c0839200 c083914c 00000006 c0961c4c |
| bf40: c0961c28 00000000 c088bf7c c088bf58 c08392ac c08391c0 c08a2ed8 c0966e78 |
| bf60: c086b874 c08a3f50 c0961c28 00000001 c088bfb4 c088bf80 c083b258 c0839248 |
| bf80: 2f800000 0f000000 c08935b4 ffffffff c08cd400 ffffffff c08cd400 c0868408 |
| bfa0: c29849c0 00000000 c088bff4 c088bfb8 c0824974 c083b1e4 ffffffff ffffffff |
| bfc0: c08245c0 00000000 00000000 c0868408 00000000 10c5387d c0892bcc c0868404 |
| bfe0: c0899440 0000406a 00000000 c088bff8 00008074 c0824824 00000000 00000000 |
| [<c02c6da0>] (strncmp+0x1c/0x84) from [<c0110a3c>] (kmem_cache_flags.isra.46.part.47+0x44/0x60) |
| [<c0110a3c>] (kmem_cache_flags.isra.46.part.47+0x44/0x60) from [<c0112070>] (__kmem_cache_create+0x3c/0x410) |
| [<c0112070>] (__kmem_cache_create+0x3c/0x410) from [<c0839190>] (create_boot_cache+0x50/0x74) |
| [<c0839190>] (create_boot_cache+0x50/0x74) from [<c0839200>] (create_kmalloc_cache+0x4c/0x88) |
| [<c0839200>] (create_kmalloc_cache+0x4c/0x88) from [<c08392ac>] (create_kmalloc_caches+0x70/0x114) |
| [<c08392ac>] (create_kmalloc_caches+0x70/0x114) from [<c083b258>] (kmem_cache_init+0x80/0xe0) |
| [<c083b258>] (kmem_cache_init+0x80/0xe0) from [<c0824974>] (start_kernel+0x15c/0x318) |
| [<c0824974>] (start_kernel+0x15c/0x318) from [<00008074>] (0x8074) |
| Code: e3520000 01a00002 089da800 e5d03000 (e5d1c000) |
| ---[ end trace 1b75b31a2719ed1d ]--- |
| Kernel panic - not syncing: Fatal exception |
| |
| Problem is that slub_debug option is not parsed before |
| create_boot_cache is called. Solve this by changing slub_debug to |
| early_param. |
| |
| Kernels 3.11, 3.10 are also affected. I am not sure about older |
| kernels. |
| |
| Christoph Lameter explains: |
| |
| kmem_cache_flags may be called with NULL parameter during early boot. |
| Skip the test in that case. |
| |
| Reported-by: Andreas Herrmann <andreas.herrmann@calxeda.com> |
| Signed-off-by: Christoph Lameter <cl@linux.com> |
| Signed-off-by: Pekka Enberg <penberg@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/slub.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/mm/slub.c |
| +++ b/mm/slub.c |
| @@ -1201,8 +1201,8 @@ static unsigned long kmem_cache_flags(un |
| /* |
| * Enable debugging if selected on the kernel commandline. |
| */ |
| - if (slub_debug && (!slub_debug_slabs || |
| - !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)))) |
| + if (slub_debug && (!slub_debug_slabs || (name && |
| + !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs))))) |
| flags |= slub_debug; |
| |
| return flags; |