squashfs: don't call kmalloc in decompressors

The decompressors may be called while in an atomic section.  So move the
kmalloc() out of this path, and into the "page actor" init function.

This fixes a regression introduced by commit
2554ff4acf1b ("squashfs: extend "page actor" to handle missing pages")

Link: https://lkml.kernel.org/r/20220822215430.15933-1-phillip@squashfs.org.uk
Fixes: 2554ff4acf1b ("squashfs: extend "page actor" to handle missing pages")
Reported-by: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 98e64fec75b77e09048757fc28ea04f2f81bf53c..e56510964b229e42170304f88ee73515f54f1e6a 100644 (file)
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -593,7 +593,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
 
                res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
 
-               kfree(actor);
+               squashfs_page_actor_free(actor);
 
                if (res == expected) {
                        int bytes;

diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c
index be4b12d31e0c36fbd04e2d56f96d13e793371f92..f1ccad519e28ccf890831a36f462f0e3ce5ba3a1 100644 (file)
--- a/fs/squashfs/file_direct.c
+++ b/fs/squashfs/file_direct.c
@@ -74,7 +74,7 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
        /* Decompress directly into the page cache buffers */
        res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
 
-       kfree(actor);
+       squashfs_page_actor_free(actor);
 
        if (res < 0)
                goto mark_errored;

diff --git a/fs/squashfs/page_actor.c b/fs/squashfs/page_actor.c
index b23b780d8f42ece1639bd4bc21ced7743ffc2643..54b93bf4a25c15b9acb2bf85cbcab6723df89e40 100644 (file)
--- a/fs/squashfs/page_actor.c
+++ b/fs/squashfs/page_actor.c
@@ -52,6 +52,7 @@ struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
        actor->buffer = buffer;
        actor->pages = pages;
        actor->next_page = 0;
+       actor->tmp_buffer = NULL;
        actor->squashfs_first_page = cache_first_page;
        actor->squashfs_next_page = cache_next_page;
        actor->squashfs_finish_page = cache_finish_page;
@@ -68,20 +69,9 @@ static void *handle_next_page(struct squashfs_page_actor *actor)
 
        if ((actor->next_page == actor->pages) ||
                        (actor->next_index != actor->page[actor->next_page]->index)) {
-               if (actor->alloc_buffer) {
-                       void *tmp_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
-
-                       if (tmp_buffer) {
-                               actor->tmp_buffer = tmp_buffer;
-                               actor->next_index++;
-                               actor->returned_pages++;
-                               return tmp_buffer;
-                       }
-               }
-
                actor->next_index++;
                actor->returned_pages++;
-               return ERR_PTR(-ENOMEM);
+               return actor->alloc_buffer ? actor->tmp_buffer : ERR_PTR(-ENOMEM);
        }
 
        actor->next_index++;
@@ -96,11 +86,10 @@ static void *direct_first_page(struct squashfs_page_actor *actor)
 
 static void *direct_next_page(struct squashfs_page_actor *actor)
 {
-       if (actor->pageaddr)
+       if (actor->pageaddr) {
                kunmap_local(actor->pageaddr);
-
-       kfree(actor->tmp_buffer);
-       actor->pageaddr = actor->tmp_buffer = NULL;
+               actor->pageaddr = NULL;
+       }
 
        return handle_next_page(actor);
 }
@@ -109,8 +98,6 @@ static void direct_finish_page(struct squashfs_page_actor *actor)
 {
        if (actor->pageaddr)
                kunmap_local(actor->pageaddr);
-
-       kfree(actor->tmp_buffer);
 }
 
 struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_info *msblk,
@@ -121,6 +108,16 @@ struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_
        if (actor == NULL)
                return NULL;
 
+       if (msblk->decompressor->alloc_buffer) {
+               actor->tmp_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
+
+               if (actor->tmp_buffer == NULL) {
+                       kfree(actor);
+                       return NULL;
+               }
+       } else
+               actor->tmp_buffer = NULL;
+
        actor->length = length ? : pages * PAGE_SIZE;
        actor->page = page;
        actor->pages = pages;
@@ -128,7 +125,6 @@ struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_
        actor->returned_pages = 0;
        actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1);
        actor->pageaddr = NULL;
-       actor->tmp_buffer = NULL;
        actor->alloc_buffer = msblk->decompressor->alloc_buffer;
        actor->squashfs_first_page = direct_first_page;
        actor->squashfs_next_page = direct_next_page;

diff --git a/fs/squashfs/page_actor.h b/fs/squashfs/page_actor.h
index 24841d28bc0fb85b630535f4c07c6c54b4aa2767..95ffbb543d913b601604ae3cc12f766bb5380295 100644 (file)
--- a/fs/squashfs/page_actor.h
+++ b/fs/squashfs/page_actor.h
@@ -29,6 +29,11 @@ extern struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
 extern struct squashfs_page_actor *squashfs_page_actor_init_special(
                                struct squashfs_sb_info *msblk,
                                struct page **page, int pages, int length);
+static inline void squashfs_page_actor_free(struct squashfs_page_actor *actor)
+{
+       kfree(actor->tmp_buffer);
+       kfree(actor);
+}
 static inline void *squashfs_first_page(struct squashfs_page_actor *actor)
 {
        return actor->squashfs_first_page(actor);