From a2b992c828f7651db369ba8f0eb0818d70232636 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 9 Jul 2020 17:42:44 -0700 Subject: debugfs: make sure we can remove u32_array files cleanly debugfs_create_u32_array() allocates a small structure to wrap the data and size information about the array. If users ever try to remove the file this leads to a leak since nothing ever frees this wrapper. That said there are no upstream users of debugfs_create_u32_array() that'd remove a u32 array file (we only have one u32 array user in CMA), so there is no real bug here. Make callers pass a wrapper they allocated. This way the lifetime management of the wrapper is on the caller, and we can avoid the potential leak in debugfs. CC: Chucheng Luo Signed-off-by: Jakub Kicinski Reviewed-by: Greg Kroah-Hartman Signed-off-by: David S. Miller --- Documentation/filesystems/debugfs.rst | 12 ++++++++---- fs/debugfs/file.c | 27 +++++++-------------------- include/linux/debugfs.h | 12 +++++++++--- mm/cma.h | 3 +++ mm/cma_debug.c | 7 ++++--- 5 files changed, 31 insertions(+), 30 deletions(-) diff --git a/Documentation/filesystems/debugfs.rst b/Documentation/filesystems/debugfs.rst index 1da7a4b7383d..728ab57a611a 100644 --- a/Documentation/filesystems/debugfs.rst +++ b/Documentation/filesystems/debugfs.rst @@ -185,13 +185,17 @@ byte offsets over a base for the register block. If you want to dump an u32 array in debugfs, you can create file with:: + struct debugfs_u32_array { + u32 *array; + u32 n_elements; + }; + void debugfs_create_u32_array(const char *name, umode_t mode, struct dentry *parent, - u32 *array, u32 elements); + struct debugfs_u32_array *array); -The "array" argument provides data, and the "elements" argument is -the number of elements in the array. Note: Once array is created its -size can not be changed. +The "array" argument wraps a pointer to the array's data and the number +of its elements. Note: Once array is created its size can not be changed. There is a helper function to create device related seq_file:: diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index ae49a55bda00..d0ed71f37511 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -918,11 +918,6 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, } EXPORT_SYMBOL_GPL(debugfs_create_blob); -struct array_data { - void *array; - u32 elements; -}; - static size_t u32_format_array(char *buf, size_t bufsize, u32 *array, int array_size) { @@ -943,8 +938,8 @@ static size_t u32_format_array(char *buf, size_t bufsize, static int u32_array_open(struct inode *inode, struct file *file) { - struct array_data *data = inode->i_private; - int size, elements = data->elements; + struct debugfs_u32_array *data = inode->i_private; + int size, elements = data->n_elements; char *buf; /* @@ -959,7 +954,7 @@ static int u32_array_open(struct inode *inode, struct file *file) buf[size] = 0; file->private_data = buf; - u32_format_array(buf, size, data->array, data->elements); + u32_format_array(buf, size, data->array, data->n_elements); return nonseekable_open(inode, file); } @@ -996,8 +991,7 @@ static const struct file_operations u32_array_fops = { * @parent: a pointer to the parent dentry for this file. This should be a * directory dentry if set. If this parameter is %NULL, then the * file will be created in the root of the debugfs filesystem. - * @array: u32 array that provides data. - * @elements: total number of elements in the array. + * @array: wrapper struct containing data pointer and size of the array. * * This function creates a file in debugfs with the given name that exports * @array as data. If the @mode variable is so set it can be read from. @@ -1005,17 +999,10 @@ static const struct file_operations u32_array_fops = { * Once array is created its size can not be changed. */ void debugfs_create_u32_array(const char *name, umode_t mode, - struct dentry *parent, u32 *array, u32 elements) + struct dentry *parent, + struct debugfs_u32_array *array) { - struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL); - - if (data == NULL) - return; - - data->array = array; - data->elements = elements; - - debugfs_create_file_unsafe(name, mode, parent, data, &u32_array_fops); + debugfs_create_file_unsafe(name, mode, parent, array, &u32_array_fops); } EXPORT_SYMBOL_GPL(debugfs_create_u32_array); diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h index 63cb3606dea7..851dd1f9a8a5 100644 --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -38,6 +38,11 @@ struct debugfs_regset32 { struct device *dev; /* Optional device for Runtime PM */ }; +struct debugfs_u32_array { + u32 *array; + u32 n_elements; +}; + extern struct dentry *arch_debugfs_dir; #define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \ @@ -136,7 +141,8 @@ void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs, int nregs, void __iomem *base, char *prefix); void debugfs_create_u32_array(const char *name, umode_t mode, - struct dentry *parent, u32 *array, u32 elements); + struct dentry *parent, + struct debugfs_u32_array *array); struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name, struct dentry *parent, @@ -316,8 +322,8 @@ static inline bool debugfs_initialized(void) } static inline void debugfs_create_u32_array(const char *name, umode_t mode, - struct dentry *parent, u32 *array, - u32 elements) + struct dentry *parent, + struct debugfs_u32_array *array) { } diff --git a/mm/cma.h b/mm/cma.h index 33c0b517733c..6698fa63279b 100644 --- a/mm/cma.h +++ b/mm/cma.h @@ -2,6 +2,8 @@ #ifndef __MM_CMA_H__ #define __MM_CMA_H__ +#include + struct cma { unsigned long base_pfn; unsigned long count; @@ -11,6 +13,7 @@ struct cma { #ifdef CONFIG_CMA_DEBUGFS struct hlist_head mem_head; spinlock_t mem_head_lock; + struct debugfs_u32_array dfs_bitmap; #endif const char *name; }; diff --git a/mm/cma_debug.c b/mm/cma_debug.c index 4e6cbe2f586e..d5bf8aa34fdc 100644 --- a/mm/cma_debug.c +++ b/mm/cma_debug.c @@ -164,7 +164,6 @@ static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry) { struct dentry *tmp; char name[16]; - int u32s; scnprintf(name, sizeof(name), "cma-%s", cma->name); @@ -180,8 +179,10 @@ static void cma_debugfs_add_one(struct cma *cma, struct dentry *root_dentry) debugfs_create_file("used", 0444, tmp, cma, &cma_used_fops); debugfs_create_file("maxchunk", 0444, tmp, cma, &cma_maxchunk_fops); - u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32)); - debugfs_create_u32_array("bitmap", 0444, tmp, (u32 *)cma->bitmap, u32s); + cma->dfs_bitmap.array = (u32 *)cma->bitmap; + cma->dfs_bitmap.n_elements = DIV_ROUND_UP(cma_bitmap_maxno(cma), + BITS_PER_BYTE * sizeof(u32)); + debugfs_create_u32_array("bitmap", 0444, tmp, &cma->dfs_bitmap); } static int __init cma_debugfs_init(void) -- cgit