[v5] PCI: rcar-ep: Fix the issue of the name parameter when calling devm_request_mem_region()

Commit Message

[e-mail] Jan. 9, 2025, 12:50 a.m. UTC

From: King Dix <[e-mail]>

When using devm_request_mem_region() to request a resource and the name
parameter is a stack string variable, it may cause errors when executing
the command `cat /proc/iomem`. Depending on the content of the memory, the
manifestations of errors may vary. One possible output may be as follows:

$ cat /proc/iomem
30000000-37ffffff :
38000000-3fffffff :

Another possibility is that garbage characters may appear after the colon.
In very rare cases, if no NUL-terminator is found in memory, the system
might crash because the string iterator may access unmapped memory above
the stack.

Fix this by replacing outbound_name with the name of the previously
requested resource. With the patch applied, the output is as follows:

$ cat /proc/iomem
30000000-37ffffff : memory2
38000000-3fffffff : memory3

Fixes: 2a6d0d63d999 ("PCI: rcar: Add endpoint mode support")

Signed-off-by: King Dix <[e-mail]>
Reviewed-by: Lad Prabhakar <[e-mail]>
Tested-by: Lad Prabhakar <[e-mail]>
---
Changes in v5:
  - Add examples of error outputs to the comment.
Changes in v4:
  - Add more information to the comment.
Changes in v3:
  - Fix the spelling issue in the comment.
Changes in v2:
  - Fix the code indentation issue.
---
 drivers/pci/controller/pcie-rcar-ep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Krzysztof Wilczyński Jan. 15, 2025, 11:21 a.m. UTC | #1

Hello,

> When using devm_request_mem_region() to request a resource and the name
> parameter is a stack string variable, it may cause errors when executing
> the command `cat /proc/iomem`. Depending on the content of the memory, the
> manifestations of errors may vary. One possible output may be as follows:
> 
> $ cat /proc/iomem
> 30000000-37ffffff :
> 38000000-3fffffff :
> 
> Another possibility is that garbage characters may appear after the colon.
> In very rare cases, if no NUL-terminator is found in memory, the system
> might crash because the string iterator may access unmapped memory above
> the stack.
> 
> Fix this by replacing outbound_name with the name of the previously
> requested resource. With the patch applied, the output is as follows:
> 
> $ cat /proc/iomem
> 30000000-37ffffff : memory2
> 38000000-3fffffff : memory3

Applied to controller/rcar-ep for v6.14, thank you!

	Krzysztof

Patch

diff --git a/drivers/pci/controller/pcie-rcar-ep.c b/drivers/pci/controller/pcie-rcar-ep.c
index 047e2cef5afc..c5e0d025bc43 100644
--- a/drivers/pci/controller/pcie-rcar-ep.c
+++ b/drivers/pci/controller/pcie-rcar-ep.c
@@ -107,7 +107,7 @@  static int rcar_pcie_parse_outbound_ranges(struct rcar_pcie_endpoint *ep,
 		}
 		if (!devm_request_mem_region(&pdev->dev, res->start,
 					     resource_size(res),
-					     outbound_name)) {
+					     res->name)) {
 			dev_err(pcie->dev, "Cannot request memory region %s.\n",
 				outbound_name);
 			return -EIO;