5.10-stable review patch. If anyone has any objections, please let me know.
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From: Eric W. Biederman ebiederm@xmission.com
[ Upstream commit 1f702603e7125a390b5cdf5ce00539781cfcc86a ]
Now that exec no longer needs to return the unshared files to their previous value there is no reason to return displaced.
Instead when unshare_fd creates a copy of the file table, call put_files_struct before returning from unshare_files.
Acked-by: Christian Brauner christian.brauner@ubuntu.com v1: https://lkml.kernel.org/r/20200817220425.9389-2-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20201120231441.29911-2-ebiederm@xmission.com Signed-off-by: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/coredump.c | 5 +---- fs/exec.c | 5 +---- include/linux/fdtable.h | 2 +- kernel/fork.c | 12 ++++++------ 4 files changed, 9 insertions(+), 15 deletions(-)
diff --git a/fs/coredump.c b/fs/coredump.c index 9d91e831ed0b2..7b085975ea163 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -590,7 +590,6 @@ void do_coredump(const kernel_siginfo_t *siginfo) int ispipe; size_t *argv = NULL; int argc = 0; - struct files_struct *displaced; /* require nonrelative corefile path and be extra careful */ bool need_suid_safe = false; bool core_dumped = false; @@ -797,11 +796,9 @@ void do_coredump(const kernel_siginfo_t *siginfo) }
/* get us an unshared descriptor table; almost always a no-op */ - retval = unshare_files(&displaced); + retval = unshare_files(); if (retval) goto close_fail; - if (displaced) - put_files_struct(displaced); if (!dump_interrupted()) { /* * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would diff --git a/fs/exec.c b/fs/exec.c index 42952cf90f4af..d5c8f085235bc 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1245,7 +1245,6 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) int begin_new_exec(struct linux_binprm * bprm) { struct task_struct *me = current; - struct files_struct *displaced; int retval;
/* Once we are committed compute the creds */ @@ -1266,11 +1265,9 @@ int begin_new_exec(struct linux_binprm * bprm) goto out;
/* Ensure the files table is not shared. */ - retval = unshare_files(&displaced); + retval = unshare_files(); if (retval) goto out; - if (displaced) - put_files_struct(displaced);
/* * Must be called _before_ exec_mmap() as bprm->mm is diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index f1a99d3e55707..b32ab2163dc2d 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -109,7 +109,7 @@ struct task_struct; struct files_struct *get_files_struct(struct task_struct *); void put_files_struct(struct files_struct *fs); void reset_files_struct(struct files_struct *); -int unshare_files(struct files_struct **); +int unshare_files(void); struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy; void do_close_on_exec(struct files_struct *); int iterate_fd(struct files_struct *, unsigned, diff --git a/kernel/fork.c b/kernel/fork.c index 633b0af1d1a73..8b8a5a172b158 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -3077,21 +3077,21 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) * the exec layer of the kernel. */
-int unshare_files(struct files_struct **displaced) +int unshare_files(void) { struct task_struct *task = current; - struct files_struct *copy = NULL; + struct files_struct *old, *copy = NULL; int error;
error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©); - if (error || !copy) { - *displaced = NULL; + if (error || !copy) return error; - } - *displaced = task->files; + + old = task->files; task_lock(task); task->files = copy; task_unlock(task); + put_files_struct(old); return 0; }