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authorMark Johnston <markj@FreeBSD.org>2022-02-08 17:34:20 +0000
committerMark Johnston <markj@FreeBSD.org>2022-02-08 17:40:41 +0000
commit300cfb96fc2253c3aff8d501d5599fcf811daa34 (patch)
treea65b0f02d8c3a92e7a5d57cdc75c34bd80e9480c
parent927aa5fefd4c69e72d44189a04fadf80e42d0ad8 (diff)
downloadsrc-300cfb96fc2253c3aff8d501d5599fcf811daa34.tar.gz
src-300cfb96fc2253c3aff8d501d5599fcf811daa34.zip
file: Make fget*() and getvnode*() consistent about initializing *fpp
Most fget*() functions initialize the output parameter to NULL. Make the externally visible interface behave consistently, and make fget_unlocked_seq() private to kern_descrip.c. This fixes at least one bug in a consumer, _filemon_wrapper_openat(), which assumes that getvnode() sets the output file pointer to NULL upon an error. Reported by: syzbot+01c0459408f896a5933a@syzkaller.appspotmail.com Reviewed by: kib MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D34190
-rw-r--r--sys/kern/kern_descrip.c12
-rw-r--r--sys/kern/vfs_syscalls.c2
-rw-r--r--sys/sys/filedesc.h3
3 files changed, 12 insertions, 5 deletions
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index d5d22ecfc522..c4cf9abde664 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -115,6 +115,8 @@ static void fdgrowtable(struct filedesc *fdp, int nfd);
static void fdgrowtable_exp(struct filedesc *fdp, int nfd);
static void fdunused(struct filedesc *fdp, int fd);
static void fdused(struct filedesc *fdp, int fd);
+static int fget_unlocked_seq(struct filedesc *fdp, int fd,
+ cap_rights_t *needrightsp, struct file **fpp, seqc_t *seqp);
static int getmaxfd(struct thread *td);
static u_long *filecaps_copy_prep(const struct filecaps *src);
static void filecaps_copy_finish(const struct filecaps *src,
@@ -2843,6 +2845,7 @@ fget_cap_locked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
FILEDESC_LOCK_ASSERT(fdp);
+ *fpp = NULL;
fde = fdeget_locked(fdp, fd);
if (fde == NULL) {
error = EBADF;
@@ -3014,7 +3017,7 @@ fgetvp_lookup_smr(int fd, struct nameidata *ndp, struct vnode **vpp, bool *fsear
}
#endif
-int
+static int
fget_unlocked_seq(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
struct file **fpp, seqc_t *seqp)
{
@@ -3112,8 +3115,10 @@ fget_unlocked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
#endif
fdt = fdp->fd_files;
- if (__predict_false((u_int)fd >= fdt->fdt_nfiles))
+ if (__predict_false((u_int)fd >= fdt->fdt_nfiles)) {
+ *fpp = NULL;
return (EBADF);
+ }
#ifdef CAPABILITIES
seq = seqc_read_notmodify(fd_seqc(fdt, fd));
fde = &fdt->fdt_ofiles[fd];
@@ -3148,6 +3153,7 @@ fget_unlocked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
out_fdrop:
fdrop(fp, curthread);
out_fallback:
+ *fpp = NULL;
return (fget_unlocked_seq(fdp, fd, needrightsp, fpp, NULL));
}
@@ -3173,6 +3179,7 @@ fget_only_user(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
MPASS(FILEDESC_IS_ONLY_USER(fdp));
+ *fpp = NULL;
if (__predict_false(fd >= fdp->fd_nfiles))
return (EBADF);
@@ -3198,6 +3205,7 @@ fget_only_user(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
MPASS(FILEDESC_IS_ONLY_USER(fdp));
+ *fpp = NULL;
if (__predict_false(fd >= fdp->fd_nfiles))
return (EBADF);
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 3e0b96051465..5549cae570f8 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -4336,6 +4336,7 @@ getvnode_path(struct thread *td, int fd, cap_rights_t *rightsp,
*/
if (__predict_false(fp->f_vnode == NULL || fp->f_ops == &badfileops)) {
fdrop(fp, td);
+ *fpp = NULL;
return (EINVAL);
}
@@ -4363,6 +4364,7 @@ getvnode(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp)
*/
if (__predict_false((*fpp)->f_ops == &path_fileops)) {
fdrop(*fpp, td);
+ *fpp = NULL;
error = EBADF;
}
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
index 6f0e74e70d3b..f003c0ff3c4b 100644
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -269,10 +269,7 @@ int fget_cap_locked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
struct file **fpp, struct filecaps *havecapsp);
int fget_cap(struct thread *td, int fd, cap_rights_t *needrightsp,
struct file **fpp, struct filecaps *havecapsp);
-
/* Return a referenced file from an unlocked descriptor. */
-int fget_unlocked_seq(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
- struct file **fpp, seqc_t *seqp);
int fget_unlocked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
struct file **fpp);
/* Return a file pointer without a ref. FILEDESC_IS_ONLY_USER must be true. */