| Message ID | 20221007065618.2169880-1-s.hauer@pengutronix.de |
|---|---|
| State | New |
| Headers | show |
| Series | PCI/sysfs: Fix double free in error path | expand |
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 <s.hauer@pengutronix.de> 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 <s.hauer@pengutronix.de> Cc: <stable@vger.kernel.org> --- 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; } /**
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 <s.hauer@pengutronix.de> > Cc: <stable@vger.kernel.org> > --- > 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 > >
[+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 <s.hauer@pengutronix.de> > 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 <s.hauer@pengutronix.de> > Cc: <stable@vger.kernel.org> > --- > 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 |
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; }
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 <s.hauer@pengutronix.de> Cc: <stable@vger.kernel.org> --- drivers/pci/pci-sysfs.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)