[PATCH v2] remoteproc: imx_rproc: allow mappings ending at region boundary

[PATCH v2] remoteproc: imx_rproc: allow mappings ending at region boundary

[Marcel Hofmann]

From: Marcel Hofmann <marcel.hofmann@ingenics-digital.com>

The address range checks in imx_rproc_da_to_sys() and
imx_rproc_da_to_va() use a strict comparison for the exclusive end
address of the requested range.

As a result, a valid request that ends exactly at the end of an address
translation or mapped memory region is rejected. For a region
[start, start + size), a request [addr, addr + len) is contained when:

    addr >= start && addr + len <= start + size

This occurs when a loadable ELF segment fills an entire mapped memory
region. This can be produced by a linker script that extends the
resource table section to the end of its designated region:

    .resource_table :
    {
      . = ALIGN(8);
      KEEP(*(.resource_table)) /* Resource table */
      . = ALIGN(8);
      . = ORIGIN(m_rsc_tbl) + LENGTH(m_rsc_tbl);
    } > m_rsc_tbl =0x00

This produces a ELF program header like:

    LOAD  0x010000 0xa4220000 0xa4220000 0x01000 0x01000 R   0x1000

In this case, the segment size matches the mapped region size exactly,
causing the address translation to fail with:

    bad phdr da 0xa4220000 mem 0x1000

Rework the upper-bound checks to allow ranges ending exactly at the region
boundary while guarding against integer overflow. 

Fixes: a0ff4aa6f010 ("remoteproc: imx_rproc: add a NXP/Freescale imx_rproc driver")
Signed-off-by: Marcel Hofmann <marcel.hofmann@ingenics-digital.com>
---

Changes in v2: 
- Reworked the bounds check to guard against 64-bit integer overflow
- Use u64 for offset instead of unsigned integer
- calculate offset first and then validate len against remaining region
  size

v1: https://lore.kernel.org/r/20260826155123.AEB731F000E9@smtp.kernel.org/

 drivers/remoteproc/imx_rproc.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
index 745ce52cd822..ea852ca143bb 100644
--- a/drivers/remoteproc/imx_rproc.c
+++ b/drivers/remoteproc/imx_rproc.c
@@ -540,6 +540,7 @@ static int imx_rproc_da_to_sys(struct imx_rproc *priv, u64 da,
 	/* parse address translation table */
 	for (i = 0; i < dcfg->att_size; i++) {
 		const struct imx_rproc_att *att = &dcfg->att[i];
+		u64 offset;
 
 		/*
 		 * Ignore entries not belong to current core:
@@ -552,9 +553,11 @@ static int imx_rproc_da_to_sys(struct imx_rproc *priv, u64 da,
 				continue;
 		}
 
-		if (da >= att->da && da + len < att->da + att->size) {
-			unsigned int offset = da - att->da;
+		if (da < att->da)
+			continue;
 
+		offset = da - att->da;
+		if (offset <= att->size && len <= att->size - offset) {
 			*sys = att->sa + offset;
 			if (is_iomem)
 				*is_iomem = att->flags & ATT_IOMEM;
@@ -585,9 +588,14 @@ static void *imx_rproc_da_to_va(struct rproc *rproc, u64 da, size_t len, bool *i
 		return NULL;
 
 	for (i = 0; i < IMX_RPROC_MEM_MAX; i++) {
-		if (sys >= priv->mem[i].sys_addr && sys + len <
-		    priv->mem[i].sys_addr +  priv->mem[i].size) {
-			unsigned int offset = sys - priv->mem[i].sys_addr;
+		u64 offset;
+
+		if (sys < priv->mem[i].sys_addr)
+			continue;
+
+		offset = sys - priv->mem[i].sys_addr;
+		if (offset <= priv->mem[i].size &&
+		    len <= priv->mem[i].size - offset) {
 			/* __force to make sparse happy with type conversion */
 			va = (__force void *)(priv->mem[i].cpu_addr + offset);
 			break;
-- 
2.55.0