linux-kernel - [PATCH -next] hugetlbfs: a terminator for hugetlb_param

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Date:   Mon,  4 Feb 2019 20:22:24 -0500
From:   Qian Cai <cai@....pw>
To:     mike.kravetz@...cle.com
Cc:     dhowells@...hat.com, viro@...iv.linux.org.uk, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Qian Cai <cai@....pw>
Subject: [PATCH -next] hugetlbfs: a terminator for hugetlb_param_specs[]

Booting up an arm64 server with CONFIG_VALIDATE_FS_PARSER=n triggers a
out-of-bounds error below, due to the commit 2284cf59cbce ("hugetlbfs:
Convert to fs_context") missed a terminator for hugetlb_param_specs[],
and causes this loop in fs_lookup_key(),

for (p = desc->specs; p->name; p++)

could not exit properly due to p->name is never be NULL.

[   91.575203] BUG: KASAN: global-out-of-bounds in fs_lookup_key+0x60/0x94
[   91.581810] Read of size 8 at addr ffff200010deeb10 by task mount/2461
[   91.597350] Call trace:
[   91.597357]  dump_backtrace+0x0/0x2b0
[   91.597361]  show_stack+0x24/0x30
[   91.597373]  dump_stack+0xc0/0xf8
[   91.623263]  print_address_description+0x64/0x2b0
[   91.627965]  kasan_report+0x150/0x1a4
[   91.627970]  __asan_report_load8_noabort+0x30/0x3c
[   91.627974]  fs_lookup_key+0x60/0x94
[   91.627977]  fs_parse+0x104/0x990
[   91.627986]  hugetlbfs_parse_param+0xc4/0x5e8
[   91.651081]  vfs_parse_fs_param+0x2e4/0x378
[   91.658118]  vfs_parse_fs_string+0xbc/0x12c
[   91.658122]  do_mount+0x11f0/0x1640
[   91.658125]  ksys_mount+0xc0/0xd0
[   91.658129]  __arm64_sys_mount+0xcc/0xe4
[   91.658137]  el0_svc_handler+0x28c/0x338
[   91.681740]  el0_svc+0x8/0xc

Fixes: 2284cf59cbce ("hugetlbfs: Convert to fs_context")
Signed-off-by: Qian Cai <cai@....pw>
---
 fs/hugetlbfs/inode.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index abf0c2eb834e..4f352743930f 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -81,6 +81,7 @@ static const struct fs_parameter_spec hugetlb_param_specs[] = {
 	fsparam_string("pagesize",	Opt_pagesize),
 	fsparam_string("size",		Opt_size),
 	fsparam_u32   ("uid",		Opt_uid),
+	{}
 };
 
 static const struct fs_parameter_description hugetlb_fs_parameters = {
-- 
2.17.2 (Apple Git-113)