From 74d92abc6143b124db03f0d341f02bde72fba6f5 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 22 Apr 2008 19:46:10 -0400 Subject: [PATCH] [PATCH] fix file and descriptor handling in perfmon Races galore... General rule: as soon as it's in descriptor table, it's over; another thread might have started IO on it/dup2() it elsewhere/dup2() something *over* it/etc. fd_install() is the very last step one should take - it's a point of no return. Besides, the damn thing leaked on failure exits... Signed-off-by: Al Viro --- arch/ia64/kernel/perfmon.c | 199 ++++++++++++++++--------------------- 1 file changed, 87 insertions(+), 112 deletions(-) diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c index 7fbb51e10bb..c1ad27de2dd 100644 --- a/arch/ia64/kernel/perfmon.c +++ b/arch/ia64/kernel/perfmon.c @@ -867,7 +867,7 @@ pfm_rvfree(void *mem, unsigned long size) } static pfm_context_t * -pfm_context_alloc(void) +pfm_context_alloc(int ctx_flags) { pfm_context_t *ctx; @@ -878,6 +878,46 @@ pfm_context_alloc(void) ctx = kzalloc(sizeof(pfm_context_t), GFP_KERNEL); if (ctx) { DPRINT(("alloc ctx @%p\n", ctx)); + + /* + * init context protection lock + */ + spin_lock_init(&ctx->ctx_lock); + + /* + * context is unloaded + */ + ctx->ctx_state = PFM_CTX_UNLOADED; + + /* + * initialization of context's flags + */ + ctx->ctx_fl_block = (ctx_flags & PFM_FL_NOTIFY_BLOCK) ? 1 : 0; + ctx->ctx_fl_system = (ctx_flags & PFM_FL_SYSTEM_WIDE) ? 1: 0; + ctx->ctx_fl_no_msg = (ctx_flags & PFM_FL_OVFL_NO_MSG) ? 1: 0; + /* + * will move to set properties + * ctx->ctx_fl_excl_idle = (ctx_flags & PFM_FL_EXCL_IDLE) ? 1: 0; + */ + + /* + * init restart semaphore to locked + */ + init_completion(&ctx->ctx_restart_done); + + /* + * activation is used in SMP only + */ + ctx->ctx_last_activation = PFM_INVALID_ACTIVATION; + SET_LAST_CPU(ctx, -1); + + /* + * initialize notification message queue + */ + ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0; + init_waitqueue_head(&ctx->ctx_msgq_wait); + init_waitqueue_head(&ctx->ctx_zombieq); + } return ctx; } @@ -2165,28 +2205,21 @@ static struct dentry_operations pfmfs_dentry_operations = { }; -static int -pfm_alloc_fd(struct file **cfile) +static struct file * +pfm_alloc_file(pfm_context_t *ctx) { - int fd, ret = 0; - struct file *file = NULL; - struct inode * inode; + struct file *file; + struct inode *inode; + struct dentry *dentry; char name[32]; struct qstr this; - fd = get_unused_fd(); - if (fd < 0) return -ENFILE; - - ret = -ENFILE; - - file = get_empty_filp(); - if (!file) goto out; - /* * allocate a new inode */ inode = new_inode(pfmfs_mnt->mnt_sb); - if (!inode) goto out; + if (!inode) + return ERR_PTR(-ENOMEM); DPRINT(("new inode ino=%ld @%p\n", inode->i_ino, inode)); @@ -2199,59 +2232,28 @@ pfm_alloc_fd(struct file **cfile) this.len = strlen(name); this.hash = inode->i_ino; - ret = -ENOMEM; - /* * allocate a new dcache entry */ - file->f_path.dentry = d_alloc(pfmfs_mnt->mnt_sb->s_root, &this); - if (!file->f_path.dentry) goto out; + dentry = d_alloc(pfmfs_mnt->mnt_sb->s_root, &this); + if (!dentry) { + iput(inode); + return ERR_PTR(-ENOMEM); + } - file->f_path.dentry->d_op = &pfmfs_dentry_operations; + dentry->d_op = &pfmfs_dentry_operations; + d_add(dentry, inode); - d_add(file->f_path.dentry, inode); - file->f_path.mnt = mntget(pfmfs_mnt); - file->f_mapping = inode->i_mapping; + file = alloc_file(pfmfs_mnt, dentry, FMODE_READ, &pfm_file_ops); + if (!file) { + dput(dentry); + return ERR_PTR(-ENFILE); + } - file->f_op = &pfm_file_ops; - file->f_mode = FMODE_READ; file->f_flags = O_RDONLY; - file->f_pos = 0; - - /* - * may have to delay until context is attached? - */ - fd_install(fd, file); - - /* - * the file structure we will use - */ - *cfile = file; - - return fd; -out: - if (file) put_filp(file); - put_unused_fd(fd); - return ret; -} - -static void -pfm_free_fd(int fd, struct file *file) -{ - struct files_struct *files = current->files; - struct fdtable *fdt; + file->private_data = ctx; - /* - * there ie no fd_uninstall(), so we do it here - */ - spin_lock(&files->file_lock); - fdt = files_fdtable(files); - rcu_assign_pointer(fdt->fd[fd], NULL); - spin_unlock(&files->file_lock); - - if (file) - put_filp(file); - put_unused_fd(fd); + return file; } static int @@ -2475,6 +2477,7 @@ pfm_setup_buffer_fmt(struct task_struct *task, struct file *filp, pfm_context_t /* link buffer format and context */ ctx->ctx_buf_fmt = fmt; + ctx->ctx_fl_is_sampling = 1; /* assume record() is defined */ /* * check if buffer format wants to use perfmon buffer allocation/mapping service @@ -2669,78 +2672,45 @@ pfm_context_create(pfm_context_t *ctx, void *arg, int count, struct pt_regs *reg { pfarg_context_t *req = (pfarg_context_t *)arg; struct file *filp; + struct path path; int ctx_flags; + int fd; int ret; /* let's check the arguments first */ ret = pfarg_is_sane(current, req); - if (ret < 0) return ret; + if (ret < 0) + return ret; ctx_flags = req->ctx_flags; ret = -ENOMEM; - ctx = pfm_context_alloc(); - if (!ctx) goto error; + fd = get_unused_fd(); + if (fd < 0) + return fd; - ret = pfm_alloc_fd(&filp); - if (ret < 0) goto error_file; + ctx = pfm_context_alloc(ctx_flags); + if (!ctx) + goto error; - req->ctx_fd = ctx->ctx_fd = ret; + filp = pfm_alloc_file(ctx); + if (IS_ERR(filp)) { + ret = PTR_ERR(filp); + goto error_file; + } - /* - * attach context to file - */ - filp->private_data = ctx; + req->ctx_fd = ctx->ctx_fd = fd; /* * does the user want to sample? */ if (pfm_uuid_cmp(req->ctx_smpl_buf_id, pfm_null_uuid)) { ret = pfm_setup_buffer_fmt(current, filp, ctx, ctx_flags, 0, req); - if (ret) goto buffer_error; + if (ret) + goto buffer_error; } - /* - * init context protection lock - */ - spin_lock_init(&ctx->ctx_lock); - - /* - * context is unloaded - */ - ctx->ctx_state = PFM_CTX_UNLOADED; - - /* - * initialization of context's flags - */ - ctx->ctx_fl_block = (ctx_flags & PFM_FL_NOTIFY_BLOCK) ? 1 : 0; - ctx->ctx_fl_system = (ctx_flags & PFM_FL_SYSTEM_WIDE) ? 1: 0; - ctx->ctx_fl_is_sampling = ctx->ctx_buf_fmt ? 1 : 0; /* assume record() is defined */ - ctx->ctx_fl_no_msg = (ctx_flags & PFM_FL_OVFL_NO_MSG) ? 1: 0; - /* - * will move to set properties - * ctx->ctx_fl_excl_idle = (ctx_flags & PFM_FL_EXCL_IDLE) ? 1: 0; - */ - - /* - * init restart semaphore to locked - */ - init_completion(&ctx->ctx_restart_done); - - /* - * activation is used in SMP only - */ - ctx->ctx_last_activation = PFM_INVALID_ACTIVATION; - SET_LAST_CPU(ctx, -1); - - /* - * initialize notification message queue - */ - ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0; - init_waitqueue_head(&ctx->ctx_msgq_wait); - init_waitqueue_head(&ctx->ctx_zombieq); - DPRINT(("ctx=%p flags=0x%x system=%d notify_block=%d excl_idle=%d no_msg=%d ctx_fd=%d \n", ctx, ctx_flags, @@ -2755,10 +2725,14 @@ pfm_context_create(pfm_context_t *ctx, void *arg, int count, struct pt_regs *reg */ pfm_reset_pmu_state(ctx); + fd_install(fd, filp); + return 0; buffer_error: - pfm_free_fd(ctx->ctx_fd, filp); + path = filp->f_path; + put_filp(filp); + path_put(&path); if (ctx->ctx_buf_fmt) { pfm_buf_fmt_exit(ctx->ctx_buf_fmt, current, NULL, regs); @@ -2767,6 +2741,7 @@ error_file: pfm_context_free(ctx); error: + put_unused_fd(fd); return ret; } -- 2.39.2