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t=1671499271; bh=cC6PVn5s+FJZaiUsnv2n67Lrx/nqLoNCbE1HweE/1Ek=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NIbaYs4M2m8pGxG5gNnyeWjXSsARxTPm0o3xC4+ZvzZoABJBbmtTtxEVp+osSB4vN 2N1whJfH2XJfjph5Jz/QHj5zw+MDfS9s7BhgE05AG7nSGdV3V4VTYAWyeECVnrlBcN C9HE3oUF4E+XIJReLlVfQrqICDsOELdukvAePnU4jDR0iwtqATIETgwkoPty4cHQgj h1G8Ww6Q12eWq1KrvR1VUYxy/mxFZlaDsK1dbObTEpqjxh2MlmX5AuP3MXzxmXQMlF O/plKfH+LG3IfcBpWEw0m2O3UKqmUUHrWtg2ctbswU0jKiKRiqSuJ1DP6lpDL9bf6O RFrnEz4UFWJOA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Hawkins Jiawei , syzbot+a3e6acd85ded5c16a709@syzkaller.appspotmail.com, Mike Kravetz , Muchun Song , Ian Kent , Andrew Morton , Sasha Levin , muchun.song@linux.dev, linux-mm@kvack.org Subject: [PATCH AUTOSEL 6.1 07/16] hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param() Date: Mon, 19 Dec 2022 20:20:44 -0500 Message-Id: <20221220012053.1222101-7-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221220012053.1222101-1-sashal@kernel.org> References: <20221220012053.1222101-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 740B0C000C X-Stat-Signature: gw6ygt8bdrhwddy6b7zk1wsqk8tgo8wb X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1671499272-572498 X-HE-Meta: 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 cyFZQged tzDgmLeSBFx8ZEUOswWm8USz/oU8VNsXrP+eJaDagvsYupHaIvRfM8o7B36CNQjSP64Yo7y34qFa0vuX3+MmApejf6wITiwk8Q/dx4D1AiwCu1XoHO6ei49jKLU2PvxoF2cFebz3xfXl9BoYTpQiF6II8mXP4c3i56AmH/ifZ4LU5KlvQ81Oh4Ob95s0fcoX7EDcC5WNj/6U0EmvkAyqmKHsOtQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Hawkins Jiawei [ Upstream commit 26215b7ee923b9251f7bb12c4e5f09dc465d35f2 ] Syzkaller reports a null-ptr-deref bug as follows: ====================================================== KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:hugetlbfs_parse_param+0x1dd/0x8e0 fs/hugetlbfs/inode.c:1380 [...] Call Trace: vfs_parse_fs_param fs/fs_context.c:148 [inline] vfs_parse_fs_param+0x1f9/0x3c0 fs/fs_context.c:129 vfs_parse_fs_string+0xdb/0x170 fs/fs_context.c:191 generic_parse_monolithic+0x16f/0x1f0 fs/fs_context.c:231 do_new_mount fs/namespace.c:3036 [inline] path_mount+0x12de/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] ====================================================== According to commit "vfs: parse: deal with zero length string value", kernel will set the param->string to null pointer in vfs_parse_fs_string() if fs string has zero length. Yet the problem is that, hugetlbfs_parse_param() will dereference the param->string, without checking whether it is a null pointer. To be more specific, if hugetlbfs_parse_param() parses an illegal mount parameter, such as "size=,", kernel will constructs struct fs_parameter with null pointer in vfs_parse_fs_string(), then passes this struct fs_parameter to hugetlbfs_parse_param(), which triggers the above null-ptr-deref bug. This patch solves it by adding sanity check on param->string in hugetlbfs_parse_param(). Link: https://lkml.kernel.org/r/20221020231609.4810-1-yin31149@gmail.com Reported-by: syzbot+a3e6acd85ded5c16a709@syzkaller.appspotmail.com Tested-by: syzbot+a3e6acd85ded5c16a709@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/0000000000005ad00405eb7148c6@google.com/ Signed-off-by: Hawkins Jiawei Reviewed-by: Mike Kravetz Cc: Hawkins Jiawei Cc: Muchun Song Cc: Ian Kent Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- fs/hugetlbfs/inode.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index df7772335dc0..8eea709e3659 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -1377,7 +1377,7 @@ static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *par case Opt_size: /* memparse() will accept a K/M/G without a digit */ - if (!isdigit(param->string[0])) + if (!param->string || !isdigit(param->string[0])) goto bad_val; ctx->max_size_opt = memparse(param->string, &rest); ctx->max_val_type = SIZE_STD; @@ -1387,7 +1387,7 @@ static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *par case Opt_nr_inodes: /* memparse() will accept a K/M/G without a digit */ - if (!isdigit(param->string[0])) + if (!param->string || !isdigit(param->string[0])) goto bad_val; ctx->nr_inodes = memparse(param->string, &rest); return 0; @@ -1403,7 +1403,7 @@ static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *par case Opt_min_size: /* memparse() will accept a K/M/G without a digit */ - if (!isdigit(param->string[0])) + if (!param->string || !isdigit(param->string[0])) goto bad_val; ctx->min_size_opt = memparse(param->string, &rest); ctx->min_val_type = SIZE_STD; -- 2.35.1