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Subject[PATCH 5.0 65/93] cifs: Fix slab-out-of-bounds when tracing SMB tcon
Date
[ Upstream commit 68ddb496800acdb46172b4981dc3753ea9b39c25 ]

This patch fixes the following KASAN report:

[ 779.044746] BUG: KASAN: slab-out-of-bounds in string+0xab/0x180
[ 779.044750] Read of size 1 at addr ffff88814f327968 by task trace-cmd/2812

[ 779.044756] CPU: 1 PID: 2812 Comm: trace-cmd Not tainted 5.1.0-rc1+ #62
[ 779.044760] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-0-ga698c89-prebuilt.qemu.org 04/01/2014
[ 779.044761] Call Trace:
[ 779.044769] dump_stack+0x5b/0x90
[ 779.044775] ? string+0xab/0x180
[ 779.044781] print_address_description+0x6c/0x23c
[ 779.044787] ? string+0xab/0x180
[ 779.044792] ? string+0xab/0x180
[ 779.044797] kasan_report.cold.3+0x1a/0x32
[ 779.044803] ? string+0xab/0x180
[ 779.044809] string+0xab/0x180
[ 779.044816] ? widen_string+0x160/0x160
[ 779.044822] ? vsnprintf+0x5bf/0x7f0
[ 779.044829] vsnprintf+0x4e7/0x7f0
[ 779.044836] ? pointer+0x4a0/0x4a0
[ 779.044841] ? seq_buf_vprintf+0x79/0xc0
[ 779.044848] seq_buf_vprintf+0x62/0xc0
[ 779.044855] trace_seq_printf+0x113/0x210
[ 779.044861] ? trace_seq_puts+0x110/0x110
[ 779.044867] ? trace_raw_output_prep+0xd8/0x110
[ 779.044876] trace_raw_output_smb3_tcon_class+0x9f/0xc0
[ 779.044882] print_trace_line+0x377/0x890
[ 779.044888] ? tracing_buffers_read+0x300/0x300
[ 779.044893] ? ring_buffer_read+0x58/0x70
[ 779.044899] s_show+0x6e/0x140
[ 779.044906] seq_read+0x505/0x6a0
[ 779.044913] vfs_read+0xaf/0x1b0
[ 779.044919] ksys_read+0xa1/0x130
[ 779.044925] ? kernel_write+0xa0/0xa0
[ 779.044931] ? __do_page_fault+0x3d5/0x620
[ 779.044938] do_syscall_64+0x63/0x150
[ 779.044944] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 779.044949] RIP: 0033:0x7f62c2c2db31
[ 779.044955] Code: fe ff ff 48 8d 3d 17 9e 09 00 48 83 ec 08 e8 96 02
02 00 66 0f 1f 44 00 00 8b 05 fa fc 2c 00 48 63 ff 85 c0 75 13 31 c0
0f 05 <48> 3d 00 f0 ff ff 77 57 f3 c3 0f 1f 44 00 00 55 53 48 89 d5 48
89
[ 779.044958] RSP: 002b:00007ffd6e116678 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[ 779.044964] RAX: ffffffffffffffda RBX: 0000560a38be9260 RCX: 00007f62c2c2db31
[ 779.044966] RDX: 0000000000002000 RSI: 00007ffd6e116710 RDI: 0000000000000003
[ 779.044966] RDX: 0000000000002000 RSI: 00007ffd6e116710 RDI: 0000000000000003
[ 779.044969] RBP: 00007f62c2ef5420 R08: 0000000000000000 R09: 0000000000000003
[ 779.044972] R10: ffffffffffffffa8 R11: 0000000000000246 R12: 00007ffd6e116710
[ 779.044975] R13: 0000000000002000 R14: 0000000000000d68 R15: 0000000000002000

[ 779.044981] Allocated by task 1257:
[ 779.044987] __kasan_kmalloc.constprop.5+0xc1/0xd0
[ 779.044992] kmem_cache_alloc+0xad/0x1a0
[ 779.044997] getname_flags+0x6c/0x2a0
[ 779.045003] user_path_at_empty+0x1d/0x40
[ 779.045008] do_faccessat+0x12a/0x330
[ 779.045012] do_syscall_64+0x63/0x150
[ 779.045017] entry_SYSCALL_64_after_hwframe+0x44/0xa9

[ 779.045019] Freed by task 1257:
[ 779.045023] __kasan_slab_free+0x12e/0x180
[ 779.045029] kmem_cache_free+0x85/0x1b0
[ 779.045034] filename_lookup.part.70+0x176/0x250
[ 779.045039] do_faccessat+0x12a/0x330
[ 779.045043] do_syscall_64+0x63/0x150
[ 779.045048] entry_SYSCALL_64_after_hwframe+0x44/0xa9

[ 779.045052] The buggy address belongs to the object at ffff88814f326600
which belongs to the cache names_cache of size 4096
[ 779.045057] The buggy address is located 872 bytes to the right of
4096-byte region [ffff88814f326600, ffff88814f327600)
[ 779.045058] The buggy address belongs to the page:
[ 779.045062] page:ffffea00053cc800 count:1 mapcount:0 mapping:ffff88815b191b40 index:0x0 compound_mapcount: 0
[ 779.045067] flags: 0x200000000010200(slab|head)
[ 779.045075] raw: 0200000000010200 dead000000000100 dead000000000200 ffff88815b191b40
[ 779.045081] raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
[ 779.045083] page dumped because: kasan: bad access detected

[ 779.045085] Memory state around the buggy address:
[ 779.045089] ffff88814f327800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 779.045093] ffff88814f327880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 779.045097] >ffff88814f327900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 779.045099] ^
[ 779.045103] ffff88814f327980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 779.045107] ffff88814f327a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 779.045109] ==================================================================
[ 779.045110] Disabling lock debugging due to kernel taint

Correctly assign tree name str for smb3_tcon event.

Signed-off-by: Paulo Alcantara (SUSE) <paulo@paulo.ac>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/trace.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/cifs/trace.h b/fs/cifs/trace.h
index 59be48206932..b49bc925fb4f 100644
--- a/fs/cifs/trace.h
+++ b/fs/cifs/trace.h
@@ -378,19 +378,19 @@ DECLARE_EVENT_CLASS(smb3_tcon_class,
__field(unsigned int, xid)
__field(__u32, tid)
__field(__u64, sesid)
- __field(const char *, unc_name)
+ __string(name, unc_name)
__field(int, rc)
),
TP_fast_assign(
__entry->xid = xid;
__entry->tid = tid;
__entry->sesid = sesid;
- __entry->unc_name = unc_name;
+ __assign_str(name, unc_name);
__entry->rc = rc;
),
TP_printk("xid=%u sid=0x%llx tid=0x%x unc_name=%s rc=%d",
__entry->xid, __entry->sesid, __entry->tid,
- __entry->unc_name, __entry->rc)
+ __get_str(name), __entry->rc)
)

#define DEFINE_SMB3_TCON_EVENT(name) \
--
2.19.1


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