6.12-stable review patch. If anyone has any objections, please let me know.

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From: Hongbo Li lihongbo22@huawei.com

[ Upstream commit 2c2b67af5f5f77fc68261a137ad65dcfb8e52506 ]

In the old mount proceedure, hostfs could only pass root directory during boot. This is because it constructed the root directory using the @root_ino event without any mount options. However, when using it with the new mount API, this step is no longer triggered. As a result, if users mounts without specifying any mount options, the @host_root_path remains uninitialized. To prevent this issue, the @host_root_path should be initialized at the time of allocation.

Reported-by: Geoffrey Thorpe geoff@geoffthorpe.net Closes: https://lore.kernel.org/all/643333a0-f434-42fb-82ac-d25a0b56f3b7@geoffthorpe... Fixes: cd140ce9f611 ("hostfs: convert hostfs to use the new mount API") Signed-off-by: Hongbo Li lihongbo22@huawei.com Link: https://patch.msgid.link/20251011092235.29880-1-lihongbo22@huawei.com Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/hostfs/hostfs_kern.c | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c index a16a7df0766cd..3e143b679156d 100644 --- a/fs/hostfs/hostfs_kern.c +++ b/fs/hostfs/hostfs_kern.c @@ -972,7 +972,7 @@ static int hostfs_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct hostfs_fs_info *fsi = fc->s_fs_info; struct fs_parse_result result; - char *host_root; + char *host_root, *tmp_root; int opt;

opt = fs_parse(fc, hostfs_param_specs, param, &result); @@ -983,11 +983,13 @@ static int hostfs_parse_param(struct fs_context *fc, struct fs_parameter *param) case Opt_hostfs: host_root = param->string; if (!*host_root) - host_root = ""; - fsi->host_root_path = - kasprintf(GFP_KERNEL, "%s/%s", root_ino, host_root); - if (fsi->host_root_path == NULL) + break; + tmp_root = kasprintf(GFP_KERNEL, "%s%s", + fsi->host_root_path, host_root); + if (!tmp_root) return -ENOMEM; + kfree(fsi->host_root_path); + fsi->host_root_path = tmp_root; break; }

@@ -997,17 +999,17 @@ static int hostfs_parse_param(struct fs_context *fc, struct fs_parameter *param) static int hostfs_parse_monolithic(struct fs_context *fc, void *data) { struct hostfs_fs_info *fsi = fc->s_fs_info; - char *host_root = (char *)data; + char *tmp_root, *host_root = (char *)data;

/* NULL is printed as '(null)' by printf(): avoid that. */ if (host_root == NULL) - host_root = ""; + return 0;

- fsi->host_root_path = - kasprintf(GFP_KERNEL, "%s/%s", root_ino, host_root); - if (fsi->host_root_path == NULL) + tmp_root = kasprintf(GFP_KERNEL, "%s%s", fsi->host_root_path, host_root); + if (!tmp_root) return -ENOMEM; - + kfree(fsi->host_root_path); + fsi->host_root_path = tmp_root; return 0; }

@@ -1042,6 +1044,11 @@ static int hostfs_init_fs_context(struct fs_context *fc) if (!fsi) return -ENOMEM;

+ fsi->host_root_path = kasprintf(GFP_KERNEL, "%s/", root_ino); + if (!fsi->host_root_path) { + kfree(fsi); + return -ENOMEM; + } fc->s_fs_info = fsi; fc->ops = &hostfs_context_ops; return 0;