diff options
| author | Zhang Zhengming | 2023-04-19 12:02:03 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2023-05-11 23:03:03 +0900 |
| commit | f6ee841ff2169d7a7d045340ee72b2b9de9f06c5 (patch) | |
| tree | 514e954f7571be8d4529eccef6f98dd9db8f1d80 /kernel | |
| parent | 5bd77c2393393a5003dc831d17a7adc2fc005f8e (diff) | |
relayfs: fix out-of-bounds access in relay_file_read
commit 43ec16f1450f4936025a9bdf1a273affdb9732c1 upstream.
There is a crash in relay_file_read, as the var from
point to the end of last subbuf.
The oops looks something like:
pc : __arch_copy_to_user+0x180/0x310
lr : relay_file_read+0x20c/0x2c8
Call trace:
__arch_copy_to_user+0x180/0x310
full_proxy_read+0x68/0x98
vfs_read+0xb0/0x1d0
ksys_read+0x6c/0xf0
__arm64_sys_read+0x20/0x28
el0_svc_common.constprop.3+0x84/0x108
do_el0_svc+0x74/0x90
el0_svc+0x1c/0x28
el0_sync_handler+0x88/0xb0
el0_sync+0x148/0x180
We get the condition by analyzing the vmcore:
1). The last produced byte and last consumed byte
both at the end of the last subbuf
2). A softirq calls function(e.g __blk_add_trace)
to write relay buffer occurs when an program is calling
relay_file_read_avail().
relay_file_read
relay_file_read_avail
relay_file_read_consume(buf, 0, 0);
//interrupted by softirq who will write subbuf
....
return 1;
//read_start point to the end of the last subbuf
read_start = relay_file_read_start_pos
//avail is equal to subsize
avail = relay_file_read_subbuf_avail
//from points to an invalid memory address
from = buf->start + read_start
//system is crashed
copy_to_user(buffer, from, avail)
Link: https://lkml.kernel.org/r/20230419040203.37676-1-zhang.zhengming@h3c.com
Fixes: 8d62fdebdaf9 ("relay file read: start-pos fix")
Signed-off-by: Zhang Zhengming <zhang.zhengming@h3c.com>
Reviewed-by: Zhao Lei <zhao_lei1@hoperun.com>
Reviewed-by: Zhou Kete <zhou.kete@h3c.com>
Reviewed-by: Pengcheng Yang <yangpc@wangsu.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/relay.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/relay.c b/kernel/relay.c index 88bcb09f0a1f..1cb4bb9f09a3 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -989,7 +989,8 @@ static size_t relay_file_read_start_pos(struct rchan_buf *buf) size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; size_t consumed = buf->subbufs_consumed % n_subbufs; - size_t read_pos = consumed * subbuf_size + buf->bytes_consumed; + size_t read_pos = (consumed * subbuf_size + buf->bytes_consumed) + % (n_subbufs * subbuf_size); read_subbuf = read_pos / subbuf_size; padding = buf->padding[read_subbuf]; |