From 48d499bd89191b359a6dbe44d32107e3021571c2 Mon Sep 17 00:00:00 2001 From: Frank Rowand Date: Thu, 8 Apr 2021 15:45:08 -0500 Subject: [PATCH] of: unittest: overlay: ensure proper alignment of copied FDT The Devicetree standard specifies an 8 byte alignment of the FDT. Code in libfdt expects this alignment for an FDT image in memory. kmemdup() returns 4 byte alignment on openrisc. Replace kmemdup() with kmalloc(), align pointer, memcpy() to get proper alignment. The 4 byte alignment exposed a related bug which triggered a crash on openrisc with: commit 79edff12060f ("scripts/dtc: Update to upstream version v1.6.0-51-g183df9e9c2b9") as reported in: https://lore.kernel.org/lkml/20210327224116.69309-1-linux@roeck-us.net/ Reported-by: Guenter Roeck Signed-off-by: Frank Rowand Link: https://lore.kernel.org/r/20210408204508.2276230-1-frowand.list@gmail.com Signed-off-by: Rob Herring --- drivers/of/of_private.h | 2 ++ drivers/of/overlay.c | 22 ++++++++++++++-------- drivers/of/unittest.c | 9 +++++++-- 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index d9e6a32..d717efb 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -8,6 +8,8 @@ * Copyright (C) 1996-2005 Paul Mackerras. */ +#define FDT_ALIGN_SIZE 8 + /** * struct alias_prop - Alias property in 'aliases' node * @link: List node to link the structure in aliases_lookup list diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c index e12c643..23effe5 100644 --- a/drivers/of/overlay.c +++ b/drivers/of/overlay.c @@ -57,7 +57,7 @@ struct fragment { * struct overlay_changeset * @id: changeset identifier * @ovcs_list: list on which we are located - * @fdt: FDT that was unflattened to create @overlay_tree + * @fdt: base of memory allocated to hold aligned FDT that was unflattened to create @overlay_tree * @overlay_tree: expanded device tree that contains the fragment nodes * @count: count of fragment structures * @fragments: fragment nodes in the overlay expanded device tree @@ -719,8 +719,8 @@ static struct device_node *find_target(struct device_node *info_node) /** * init_overlay_changeset() - initialize overlay changeset from overlay tree * @ovcs: Overlay changeset to build - * @fdt: the FDT that was unflattened to create @tree - * @tree: Contains all the overlay fragments and overlay fixup nodes + * @fdt: base of memory allocated to hold aligned FDT that was unflattened to create @tree + * @tree: Contains the overlay fragments and overlay fixup nodes * * Initialize @ovcs. Populate @ovcs->fragments with node information from * the top level of @tree. The relevant top level nodes are the fragment @@ -873,7 +873,7 @@ static void free_overlay_changeset(struct overlay_changeset *ovcs) * internal documentation * * of_overlay_apply() - Create and apply an overlay changeset - * @fdt: the FDT that was unflattened to create @tree + * @fdt: base of memory allocated to hold the aligned FDT * @tree: Expanded overlay device tree * @ovcs_id: Pointer to overlay changeset id * @@ -953,7 +953,9 @@ static int of_overlay_apply(const void *fdt, struct device_node *tree, /* * after overlay_notify(), ovcs->overlay_tree related pointers may have * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree; - * and can not free fdt, aka ovcs->fdt + * and can not free memory containing aligned fdt. The aligned fdt + * is contained within the memory at ovcs->fdt, possibly at an offset + * from ovcs->fdt. */ ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY); if (ret) { @@ -1014,7 +1016,8 @@ out: int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size, int *ovcs_id) { - const void *new_fdt; + void *new_fdt; + void *new_fdt_align; int ret; u32 size; struct device_node *overlay_root = NULL; @@ -1036,11 +1039,14 @@ int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size, * Must create permanent copy of FDT because of_fdt_unflatten_tree() * will create pointers to the passed in FDT in the unflattened tree. */ - new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL); + new_fdt = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL); if (!new_fdt) return -ENOMEM; - of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root); + new_fdt_align = PTR_ALIGN(new_fdt, FDT_ALIGN_SIZE); + memcpy(new_fdt_align, overlay_fdt, size); + + of_fdt_unflatten_tree(new_fdt_align, NULL, &overlay_root); if (!overlay_root) { pr_err("unable to unflatten overlay_fdt\n"); ret = -EINVAL; diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c index f9b5b69..819a20a 100644 --- a/drivers/of/unittest.c +++ b/drivers/of/unittest.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -1408,6 +1409,7 @@ static void attach_node_and_children(struct device_node *np) static int __init unittest_data_add(void) { void *unittest_data; + void *unittest_data_align; struct device_node *unittest_data_node = NULL, *np; /* * __dtb_testcases_begin[] and __dtb_testcases_end[] are magically @@ -1425,11 +1427,14 @@ static int __init unittest_data_add(void) } /* creating copy */ - unittest_data = kmemdup(__dtb_testcases_begin, size, GFP_KERNEL); + unittest_data = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL); if (!unittest_data) return -ENOMEM; - ret = of_fdt_unflatten_tree(unittest_data, NULL, &unittest_data_node); + unittest_data_align = PTR_ALIGN(unittest_data, FDT_ALIGN_SIZE); + memcpy(unittest_data_align, __dtb_testcases_begin, size); + + ret = of_fdt_unflatten_tree(unittest_data_align, NULL, &unittest_data_node); if (!ret) { pr_warn("%s: unflatten testcases tree failed\n", __func__); kfree(unittest_data); -- 2.7.4