2020-10-22 20:26:14

by Zhiqiang Liu

Subject: [PATCH] fuse: fix potential accessing NULL pointer problem in fuse_send_init()

In fuse_send_init func, ia is allocated by calling kzalloc func, and
we donot check whether ia is NULL before using it. Thus, if allocating
ia fails, accessing NULL pointer problem will occur.

Here, we will call process_init_reply func if ia is NULL.

Fixes: 615047eff108 ("fuse: convert init to simple api")
Signed-off-by: Zhiqiang Liu <[email protected]>
Signed-off-by: Haotian Li <[email protected]>
---
fs/fuse/inode.c | 161 ++++++++++++++++++++++++++----------------------
1 file changed, 87 insertions(+), 74 deletions(-)

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 581329203d68..bb526d8cf5b0 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -898,88 +898,97 @@ struct fuse_init_args {
static void process_init_reply(struct fuse_conn *fc, struct fuse_args *args,
int error)
{
- struct fuse_init_args *ia = container_of(args, typeof(*ia), args);
- struct fuse_init_out *arg = &ia->out;
+ struct fuse_init_args *ia;
+ struct fuse_init_out *arg;
+ unsigned long ra_pages;

- if (error || arg->major != FUSE_KERNEL_VERSION)
+ if (!args) {
fc->conn_error = 1;
- else {
- unsigned long ra_pages;
+ goto out;
+ }

- process_init_limits(fc, arg);
+ ia = container_of(args, typeof(*ia), args);
+ arg = &ia->out;
+ if (error || arg->major != FUSE_KERNEL_VERSION) {
+ fc->conn_error = 1;
+ goto out_free_ia;
+ }

- if (arg->minor >= 6) {
- ra_pages = arg->max_readahead / PAGE_SIZE;
- if (arg->flags & FUSE_ASYNC_READ)
- fc->async_read = 1;
- if (!(arg->flags & FUSE_POSIX_LOCKS))
- fc->no_lock = 1;
- if (arg->minor >= 17) {
- if (!(arg->flags & FUSE_FLOCK_LOCKS))
- fc->no_flock = 1;
- } else {
- if (!(arg->flags & FUSE_POSIX_LOCKS))
- fc->no_flock = 1;
- }
- if (arg->flags & FUSE_ATOMIC_O_TRUNC)
- fc->atomic_o_trunc = 1;
- if (arg->minor >= 9) {
- /* LOOKUP has dependency on proto version */
- if (arg->flags & FUSE_EXPORT_SUPPORT)
- fc->export_support = 1;
- }
- if (arg->flags & FUSE_BIG_WRITES)
- fc->big_writes = 1;
- if (arg->flags & FUSE_DONT_MASK)
- fc->dont_mask = 1;
- if (arg->flags & FUSE_AUTO_INVAL_DATA)
- fc->auto_inval_data = 1;
- else if (arg->flags & FUSE_EXPLICIT_INVAL_DATA)
- fc->explicit_inval_data = 1;
- if (arg->flags & FUSE_DO_READDIRPLUS) {
- fc->do_readdirplus = 1;
- if (arg->flags & FUSE_READDIRPLUS_AUTO)
- fc->readdirplus_auto = 1;
- }
- if (arg->flags & FUSE_ASYNC_DIO)
- fc->async_dio = 1;
- if (arg->flags & FUSE_WRITEBACK_CACHE)
- fc->writeback_cache = 1;
- if (arg->flags & FUSE_PARALLEL_DIROPS)
- fc->parallel_dirops = 1;
- if (arg->flags & FUSE_HANDLE_KILLPRIV)
- fc->handle_killpriv = 1;
- if (arg->time_gran && arg->time_gran <= 1000000000)
- fc->sb->s_time_gran = arg->time_gran;
- if ((arg->flags & FUSE_POSIX_ACL)) {
- fc->default_permissions = 1;
- fc->posix_acl = 1;
- fc->sb->s_xattr = fuse_acl_xattr_handlers;
- }
- if (arg->flags & FUSE_CACHE_SYMLINKS)
- fc->cache_symlinks = 1;
- if (arg->flags & FUSE_ABORT_ERROR)
- fc->abort_err = 1;
- if (arg->flags & FUSE_MAX_PAGES) {
- fc->max_pages =
- min_t(unsigned int, FUSE_MAX_MAX_PAGES,
- max_t(unsigned int, arg->max_pages, 1));
- }
- } else {
- ra_pages = fc->max_read / PAGE_SIZE;
+ process_init_limits(fc, arg);
+
+ if (arg->minor >= 6) {
+ ra_pages = arg->max_readahead / PAGE_SIZE;
+ if (arg->flags & FUSE_ASYNC_READ)
+ fc->async_read = 1;
+ if (!(arg->flags & FUSE_POSIX_LOCKS))
fc->no_lock = 1;
- fc->no_flock = 1;
+ if (arg->minor >= 17) {
+ if (!(arg->flags & FUSE_FLOCK_LOCKS))
+ fc->no_flock = 1;
+ } else {
+ if (!(arg->flags & FUSE_POSIX_LOCKS))
+ fc->no_flock = 1;
}
-
- fc->sb->s_bdi->ra_pages =
- min(fc->sb->s_bdi->ra_pages, ra_pages);
- fc->minor = arg->minor;
- fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
- fc->max_write = max_t(unsigned, 4096, fc->max_write);
- fc->conn_init = 1;
+ if (arg->flags & FUSE_ATOMIC_O_TRUNC)
+ fc->atomic_o_trunc = 1;
+ if (arg->minor >= 9) {
+ /* LOOKUP has dependency on proto version */
+ if (arg->flags & FUSE_EXPORT_SUPPORT)
+ fc->export_support = 1;
+ }
+ if (arg->flags & FUSE_BIG_WRITES)
+ fc->big_writes = 1;
+ if (arg->flags & FUSE_DONT_MASK)
+ fc->dont_mask = 1;
+ if (arg->flags & FUSE_AUTO_INVAL_DATA)
+ fc->auto_inval_data = 1;
+ else if (arg->flags & FUSE_EXPLICIT_INVAL_DATA)
+ fc->explicit_inval_data = 1;
+ if (arg->flags & FUSE_DO_READDIRPLUS) {
+ fc->do_readdirplus = 1;
+ if (arg->flags & FUSE_READDIRPLUS_AUTO)
+ fc->readdirplus_auto = 1;
+ }
+ if (arg->flags & FUSE_ASYNC_DIO)
+ fc->async_dio = 1;
+ if (arg->flags & FUSE_WRITEBACK_CACHE)
+ fc->writeback_cache = 1;
+ if (arg->flags & FUSE_PARALLEL_DIROPS)
+ fc->parallel_dirops = 1;
+ if (arg->flags & FUSE_HANDLE_KILLPRIV)
+ fc->handle_killpriv = 1;
+ if (arg->time_gran && arg->time_gran <= 1000000000)
+ fc->sb->s_time_gran = arg->time_gran;
+ if ((arg->flags & FUSE_POSIX_ACL)) {
+ fc->default_permissions = 1;
+ fc->posix_acl = 1;
+ fc->sb->s_xattr = fuse_acl_xattr_handlers;
+ }
+ if (arg->flags & FUSE_CACHE_SYMLINKS)
+ fc->cache_symlinks = 1;
+ if (arg->flags & FUSE_ABORT_ERROR)
+ fc->abort_err = 1;
+ if (arg->flags & FUSE_MAX_PAGES) {
+ fc->max_pages =
+ min_t(unsigned int, FUSE_MAX_MAX_PAGES,
+ max_t(unsigned int, arg->max_pages, 1));
+ }
+ } else {
+ ra_pages = fc->max_read / PAGE_SIZE;
+ fc->no_lock = 1;
+ fc->no_flock = 1;
}
- kfree(ia);

+ fc->sb->s_bdi->ra_pages =
+ min(fc->sb->s_bdi->ra_pages, ra_pages);
+ fc->minor = arg->minor;
+ fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
+ fc->max_write = max_t(unsigned int, 4096, fc->max_write);
+ fc->conn_init = 1;
+
+out_free_ia:
+ kfree(ia);
+out:
fuse_set_initialized(fc);
wake_up_all(&fc->blocked_waitq);
}
@@ -989,6 +998,10 @@ void fuse_send_init(struct fuse_conn *fc)
struct fuse_init_args *ia;

ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
+ if (!ia) {
+ process_init_reply(fc, NULL, -ENOTCONN);
+ return;
+ }

ia->in.major = FUSE_KERNEL_VERSION;
ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
--
2.19.1

2020-10-28 06:11:59

by Zhiqiang Liu

Subject: Re: [PATCH] fuse: fix potential accessing NULL pointer problem in fuse_send_init()

friendly ping...

On 2020/10/22 22:51, Zhiqiang Liu wrote:
>
> In fuse_send_init func, ia is allocated by calling kzalloc func, and
> we donot check whether ia is NULL before using it. Thus, if allocating
> ia fails, accessing NULL pointer problem will occur.
>
> Here, we will call process_init_reply func if ia is NULL.
>
> Fixes: 615047eff108 ("fuse: convert init to simple api")
> Signed-off-by: Zhiqiang Liu <[email protected]>
> Signed-off-by: Haotian Li <[email protected]>
> ---
> fs/fuse/inode.c | 161 ++++++++++++++++++++++++++----------------------
> 1 file changed, 87 insertions(+), 74 deletions(-)
>
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index 581329203d68..bb526d8cf5b0 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -898,88 +898,97 @@ struct fuse_init_args {
> static void process_init_reply(struct fuse_conn *fc, struct fuse_args *args,
> int error)
> {
> - struct fuse_init_args *ia = container_of(args, typeof(*ia), args);
> - struct fuse_init_out *arg = &ia->out;
> + struct fuse_init_args *ia;
> + struct fuse_init_out *arg;
> + unsigned long ra_pages;
>
> - if (error || arg->major != FUSE_KERNEL_VERSION)
> + if (!args) {
> fc->conn_error = 1;
> - else {
> - unsigned long ra_pages;
> + goto out;
> + }
>
> - process_init_limits(fc, arg);
> + ia = container_of(args, typeof(*ia), args);
> + arg = &ia->out;
> + if (error || arg->major != FUSE_KERNEL_VERSION) {
> + fc->conn_error = 1;
> + goto out_free_ia;
> + }
>
> - if (arg->minor >= 6) {
> - ra_pages = arg->max_readahead / PAGE_SIZE;
> - if (arg->flags & FUSE_ASYNC_READ)
> - fc->async_read = 1;
> - if (!(arg->flags & FUSE_POSIX_LOCKS))
> - fc->no_lock = 1;
> - if (arg->minor >= 17) {
> - if (!(arg->flags & FUSE_FLOCK_LOCKS))
> - fc->no_flock = 1;
> - } else {
> - if (!(arg->flags & FUSE_POSIX_LOCKS))
> - fc->no_flock = 1;
> - }
> - if (arg->flags & FUSE_ATOMIC_O_TRUNC)
> - fc->atomic_o_trunc = 1;
> - if (arg->minor >= 9) {
> - /* LOOKUP has dependency on proto version */
> - if (arg->flags & FUSE_EXPORT_SUPPORT)
> - fc->export_support = 1;
> - }
> - if (arg->flags & FUSE_BIG_WRITES)
> - fc->big_writes = 1;
> - if (arg->flags & FUSE_DONT_MASK)
> - fc->dont_mask = 1;
> - if (arg->flags & FUSE_AUTO_INVAL_DATA)
> - fc->auto_inval_data = 1;
> - else if (arg->flags & FUSE_EXPLICIT_INVAL_DATA)
> - fc->explicit_inval_data = 1;
> - if (arg->flags & FUSE_DO_READDIRPLUS) {
> - fc->do_readdirplus = 1;
> - if (arg->flags & FUSE_READDIRPLUS_AUTO)
> - fc->readdirplus_auto = 1;
> - }
> - if (arg->flags & FUSE_ASYNC_DIO)
> - fc->async_dio = 1;
> - if (arg->flags & FUSE_WRITEBACK_CACHE)
> - fc->writeback_cache = 1;
> - if (arg->flags & FUSE_PARALLEL_DIROPS)
> - fc->parallel_dirops = 1;
> - if (arg->flags & FUSE_HANDLE_KILLPRIV)
> - fc->handle_killpriv = 1;
> - if (arg->time_gran && arg->time_gran <= 1000000000)
> - fc->sb->s_time_gran = arg->time_gran;
> - if ((arg->flags & FUSE_POSIX_ACL)) {
> - fc->default_permissions = 1;
> - fc->posix_acl = 1;
> - fc->sb->s_xattr = fuse_acl_xattr_handlers;
> - }
> - if (arg->flags & FUSE_CACHE_SYMLINKS)
> - fc->cache_symlinks = 1;
> - if (arg->flags & FUSE_ABORT_ERROR)
> - fc->abort_err = 1;
> - if (arg->flags & FUSE_MAX_PAGES) {
> - fc->max_pages =
> - min_t(unsigned int, FUSE_MAX_MAX_PAGES,
> - max_t(unsigned int, arg->max_pages, 1));
> - }
> - } else {
> - ra_pages = fc->max_read / PAGE_SIZE;
> + process_init_limits(fc, arg);
> +
> + if (arg->minor >= 6) {
> + ra_pages = arg->max_readahead / PAGE_SIZE;
> + if (arg->flags & FUSE_ASYNC_READ)
> + fc->async_read = 1;
> + if (!(arg->flags & FUSE_POSIX_LOCKS))
> fc->no_lock = 1;
> - fc->no_flock = 1;
> + if (arg->minor >= 17) {
> + if (!(arg->flags & FUSE_FLOCK_LOCKS))
> + fc->no_flock = 1;
> + } else {
> + if (!(arg->flags & FUSE_POSIX_LOCKS))
> + fc->no_flock = 1;
> }
> -
> - fc->sb->s_bdi->ra_pages =
> - min(fc->sb->s_bdi->ra_pages, ra_pages);
> - fc->minor = arg->minor;
> - fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
> - fc->max_write = max_t(unsigned, 4096, fc->max_write);
> - fc->conn_init = 1;
> + if (arg->flags & FUSE_ATOMIC_O_TRUNC)
> + fc->atomic_o_trunc = 1;
> + if (arg->minor >= 9) {
> + /* LOOKUP has dependency on proto version */
> + if (arg->flags & FUSE_EXPORT_SUPPORT)
> + fc->export_support = 1;
> + }
> + if (arg->flags & FUSE_BIG_WRITES)
> + fc->big_writes = 1;
> + if (arg->flags & FUSE_DONT_MASK)
> + fc->dont_mask = 1;
> + if (arg->flags & FUSE_AUTO_INVAL_DATA)
> + fc->auto_inval_data = 1;
> + else if (arg->flags & FUSE_EXPLICIT_INVAL_DATA)
> + fc->explicit_inval_data = 1;
> + if (arg->flags & FUSE_DO_READDIRPLUS) {
> + fc->do_readdirplus = 1;
> + if (arg->flags & FUSE_READDIRPLUS_AUTO)
> + fc->readdirplus_auto = 1;
> + }
> + if (arg->flags & FUSE_ASYNC_DIO)
> + fc->async_dio = 1;
> + if (arg->flags & FUSE_WRITEBACK_CACHE)
> + fc->writeback_cache = 1;
> + if (arg->flags & FUSE_PARALLEL_DIROPS)
> + fc->parallel_dirops = 1;
> + if (arg->flags & FUSE_HANDLE_KILLPRIV)
> + fc->handle_killpriv = 1;
> + if (arg->time_gran && arg->time_gran <= 1000000000)
> + fc->sb->s_time_gran = arg->time_gran;
> + if ((arg->flags & FUSE_POSIX_ACL)) {
> + fc->default_permissions = 1;
> + fc->posix_acl = 1;
> + fc->sb->s_xattr = fuse_acl_xattr_handlers;
> + }
> + if (arg->flags & FUSE_CACHE_SYMLINKS)
> + fc->cache_symlinks = 1;
> + if (arg->flags & FUSE_ABORT_ERROR)
> + fc->abort_err = 1;
> + if (arg->flags & FUSE_MAX_PAGES) {
> + fc->max_pages =
> + min_t(unsigned int, FUSE_MAX_MAX_PAGES,
> + max_t(unsigned int, arg->max_pages, 1));
> + }
> + } else {
> + ra_pages = fc->max_read / PAGE_SIZE;
> + fc->no_lock = 1;
> + fc->no_flock = 1;
> }
> - kfree(ia);
>
> + fc->sb->s_bdi->ra_pages =
> + min(fc->sb->s_bdi->ra_pages, ra_pages);
> + fc->minor = arg->minor;
> + fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
> + fc->max_write = max_t(unsigned int, 4096, fc->max_write);
> + fc->conn_init = 1;
> +
> +out_free_ia:
> + kfree(ia);
> +out:
> fuse_set_initialized(fc);
> wake_up_all(&fc->blocked_waitq);
> }
> @@ -989,6 +998,10 @@ void fuse_send_init(struct fuse_conn *fc)
> struct fuse_init_args *ia;
>
> ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
> + if (!ia) {
> + process_init_reply(fc, NULL, -ENOTCONN);
> + return;
> + }
>
> ia->in.major = FUSE_KERNEL_VERSION;
> ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
>

2020-10-29 15:29:17

by Miklos Szeredi

Subject: Re: [PATCH] fuse: fix potential accessing NULL pointer problem in fuse_send_init()

On Thu, Oct 22, 2020 at 4:52 PM Zhiqiang Liu <[email protected]> wrote:
>
>
> In fuse_send_init func, ia is allocated by calling kzalloc func, and
> we donot check whether ia is NULL before using it. Thus, if allocating
> ia fails, accessing NULL pointer problem will occur.

Note the __GFP_NOFAIL flag for kzalloc(), which ensures that it will not fail.

Thanks,
Miklos

2020-10-30 03:04:13

by Zhiqiang Liu

Subject: Re: [PATCH] fuse: fix potential accessing NULL pointer problem in fuse_send_init()

On 2020/10/29 23:25, Miklos Szeredi wrote:
> On Thu, Oct 22, 2020 at 4:52 PM Zhiqiang Liu <[email protected]> wrote:
>>
>>
>> In fuse_send_init func, ia is allocated by calling kzalloc func, and
>> we donot check whether ia is NULL before using it. Thus, if allocating
>> ia fails, accessing NULL pointer problem will occur.
>
> Note the __GFP_NOFAIL flag for kzalloc(), which ensures that it will not fail.

Thanks for your reply.
Please ignore this patch.