git: 7ac2a6354f35 - stable/13 - file: Make fget*() and getvnode*() consistent about initializing *fpp
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Date: Wed, 16 Feb 2022 16:52:42 UTC
The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=7ac2a6354f35b785f58a9330bcd0496d0f382137 commit 7ac2a6354f35b785f58a9330bcd0496d0f382137 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2022-02-08 17:34:20 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2022-02-16 16:52:31 +0000 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 Sponsored by: The FreeBSD Foundation (cherry picked from commit 300cfb96fc2253c3aff8d501d5599fcf811daa34) --- sys/kern/kern_descrip.c | 12 ++++++++++-- sys/kern/vfs_syscalls.c | 2 ++ sys/sys/filedesc.h | 3 --- 3 files changed, 12 insertions(+), 5 deletions(-) diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c index f3dd675d806a..025259dd20f3 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, @@ -2931,6 +2933,7 @@ 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; @@ -3102,7 +3105,7 @@ 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) { @@ -3200,8 +3203,10 @@ 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]; @@ -3236,6 +3241,7 @@ 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)); } @@ -3261,6 +3267,7 @@ 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); @@ -3286,6 +3293,7 @@ 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 6dc6ca43a774..3d1e7d9c73fa 100644 --- a/sys/kern/vfs_syscalls.c +++ b/sys/kern/vfs_syscalls.c @@ -4306,6 +4306,7 @@ getvnode_path(struct thread *td, int fd, cap_rights_t *rightsp, */ if (fp->f_vnode == NULL || fp->f_ops == &badfileops) { fdrop(fp, td); + *fpp = NULL; return (EINVAL); } @@ -4331,6 +4332,7 @@ getvnode(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp) */ if (error == 0 && (*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 f17fdf601ba1..9ae7b543e4a1 100644 --- a/sys/sys/filedesc.h +++ b/sys/sys/filedesc.h @@ -273,10 +273,7 @@ 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. */