When pci_create_attr() fails then pci_remove_resource_files() is called
which will iterate over the res_attr[_wc] arrays and frees every non
NULL entry. To avoid a double free here we have to set the failed entry
to NULL in pci_create_attr() when freeing it.
Fixes: b562ec8f74e4 ("PCI: Don't leak memory if sysfs_create_bin_file() fails")
Signed-off-by: Sascha Hauer <[email protected]>
Cc: <[email protected]>
---
drivers/pci/pci-sysfs.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index fc804e08e3cb5..a07381d46ddae 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1196,8 +1196,13 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
res_attr->size = pci_resource_len(pdev, num);
res_attr->private = (void *)(unsigned long)num;
retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
- if (retval)
+ if (retval) {
+ if (write_combine)
+ pdev->res_attr_wc[num] = NULL;
+ else
+ pdev->res_attr[num] = NULL;
kfree(res_attr);
+ }
return retval;
}
--
2.30.2
On Fri, Oct 07, 2022 at 08:56:18AM +0200, Sascha Hauer wrote:
> When pci_create_attr() fails then pci_remove_resource_files() is called
> which will iterate over the res_attr[_wc] arrays and frees every non
> NULL entry. To avoid a double free here we have to set the failed entry
> to NULL in pci_create_attr() when freeing it.
>
You might consider applying this alternative version instead which IMO
looks a bit better.
Sascha
-------------------------------8<-----------------------------
From fe8e0e6f914c14395c751b7dc165967b12427995 Mon Sep 17 00:00:00 2001
From: Sascha Hauer <[email protected]>
Date: Fri, 7 Oct 2022 07:35:35 +0200
Subject: [PATCH] PCI/sysfs: Fix double free in error path
When pci_create_attr() fails then pci_remove_resource_files() is called
which will iterate over the res_attr[_wc] arrays and frees every non
NULL entry. To avoid a double free here set the array entry only after
it's clear we successfully initialized it.
Fixes: b562ec8f74e4 ("PCI: Don't leak memory if sysfs_create_bin_file() fails")
Signed-off-by: Sascha Hauer <[email protected]>
Cc: <[email protected]>
---
drivers/pci/pci-sysfs.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index fc804e08e3cb5..6dd4050c9f2ed 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1174,11 +1174,9 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
sysfs_bin_attr_init(res_attr);
if (write_combine) {
- pdev->res_attr_wc[num] = res_attr;
sprintf(res_attr_name, "resource%d_wc", num);
res_attr->mmap = pci_mmap_resource_wc;
} else {
- pdev->res_attr[num] = res_attr;
sprintf(res_attr_name, "resource%d", num);
if (pci_resource_flags(pdev, num) & IORESOURCE_IO) {
res_attr->read = pci_read_resource_io;
@@ -1196,10 +1194,17 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
res_attr->size = pci_resource_len(pdev, num);
res_attr->private = (void *)(unsigned long)num;
retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
- if (retval)
+ if (retval) {
kfree(res_attr);
+ return retval;
+ }
+
+ if (write_combine)
+ pdev->res_attr_wc[num] = res_attr;
+ else
+ pdev->res_attr[num] = res_attr;
- return retval;
+ return 0;
}
/**
--
2.30.2
--
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Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
Hi Bjorn,
On Fri, Oct 07, 2022 at 08:56:18AM +0200, Sascha Hauer wrote:
> When pci_create_attr() fails then pci_remove_resource_files() is called
> which will iterate over the res_attr[_wc] arrays and frees every non
> NULL entry. To avoid a double free here we have to set the failed entry
> to NULL in pci_create_attr() when freeing it.
>
> Fixes: b562ec8f74e4 ("PCI: Don't leak memory if sysfs_create_bin_file() fails")
> Signed-off-by: Sascha Hauer <[email protected]>
> Cc: <[email protected]>
> ---
> drivers/pci/pci-sysfs.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
Any input to this one? There's this long unfixed race condition
described here:
https://patchwork.kernel.org/project/linux-pci/patch/20200716110423.xtfyb3n6tn5ixedh@pali/#23547255
And this patch at least prevents my system from crashing when this race
condition occurs.
Sascha
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index fc804e08e3cb5..a07381d46ddae 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1196,8 +1196,13 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
> res_attr->size = pci_resource_len(pdev, num);
> res_attr->private = (void *)(unsigned long)num;
> retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
> - if (retval)
> + if (retval) {
> + if (write_combine)
> + pdev->res_attr_wc[num] = NULL;
> + else
> + pdev->res_attr[num] = NULL;
> kfree(res_attr);
> + }
>
> return retval;
> }
> --
> 2.30.2
>
>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
[+cc Sergey, Alex, Krzysztof since you all posted similar patches in
the past]
On Fri, Oct 07, 2022 at 09:07:35AM +0200, Sascha Hauer wrote:
> On Fri, Oct 07, 2022 at 08:56:18AM +0200, Sascha Hauer wrote:
> > When pci_create_attr() fails then pci_remove_resource_files() is called
> > which will iterate over the res_attr[_wc] arrays and frees every non
> > NULL entry. To avoid a double free here we have to set the failed entry
> > to NULL in pci_create_attr() when freeing it.
> >
>
> You might consider applying this alternative version instead which IMO
> looks a bit better.
Thanks, I agree, I like how this one doesn't set res_attr[] until we
know we're going to return success.
Applied to pci/sysfs for v6.2, thanks!
> -------------------------------8<-----------------------------
>
> From fe8e0e6f914c14395c751b7dc165967b12427995 Mon Sep 17 00:00:00 2001
> From: Sascha Hauer <[email protected]>
> Date: Fri, 7 Oct 2022 07:35:35 +0200
> Subject: [PATCH] PCI/sysfs: Fix double free in error path
>
> When pci_create_attr() fails then pci_remove_resource_files() is called
> which will iterate over the res_attr[_wc] arrays and frees every non
> NULL entry. To avoid a double free here set the array entry only after
> it's clear we successfully initialized it.
>
> Fixes: b562ec8f74e4 ("PCI: Don't leak memory if sysfs_create_bin_file() fails")
> Signed-off-by: Sascha Hauer <[email protected]>
> Cc: <[email protected]>
> ---
> drivers/pci/pci-sysfs.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index fc804e08e3cb5..6dd4050c9f2ed 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1174,11 +1174,9 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
>
> sysfs_bin_attr_init(res_attr);
> if (write_combine) {
> - pdev->res_attr_wc[num] = res_attr;
> sprintf(res_attr_name, "resource%d_wc", num);
> res_attr->mmap = pci_mmap_resource_wc;
> } else {
> - pdev->res_attr[num] = res_attr;
> sprintf(res_attr_name, "resource%d", num);
> if (pci_resource_flags(pdev, num) & IORESOURCE_IO) {
> res_attr->read = pci_read_resource_io;
> @@ -1196,10 +1194,17 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
> res_attr->size = pci_resource_len(pdev, num);
> res_attr->private = (void *)(unsigned long)num;
> retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
> - if (retval)
> + if (retval) {
> kfree(res_attr);
> + return retval;
> + }
> +
> + if (write_combine)
> + pdev->res_attr_wc[num] = res_attr;
> + else
> + pdev->res_attr[num] = res_attr;
>
> - return retval;
> + return 0;
> }
>
> /**
> --
> 2.30.2
>
> --
> Pengutronix e.K. | |
> Steuerwalder Str. 21 | http://www.pengutronix.de/ |
> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |