{"id":2232234,"url":"http://patchwork.ozlabs.org/api/patches/2232234/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260504022231.15501-1-kartikey406@gmail.com/","project":{"id":28,"url":"http://patchwork.ozlabs.org/api/projects/28/?format=json","name":"Linux PCI development","link_name":"linux-pci","list_id":"linux-pci.vger.kernel.org","list_email":"linux-pci@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260504022231.15501-1-kartikey406@gmail.com>","list_archive_url":null,"date":"2026-05-04T02:22:31","name":"[v2] PCI/proc: check user access return values in proc_bus_pci_{read,write}()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"0a29cfa213bb8ca6363afdfe5b7f5f11a9bd387b","submitter":{"id":91725,"url":"http://patchwork.ozlabs.org/api/people/91725/?format=json","name":"Deepanshu Kartikey","email":"kartikey406@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260504022231.15501-1-kartikey406@gmail.com/mbox/","series":[{"id":502601,"url":"http://patchwork.ozlabs.org/api/series/502601/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/list/?series=502601","date":"2026-05-04T02:22:31","name":"[v2] PCI/proc: check user access return values in proc_bus_pci_{read,write}()","version":2,"mbox":"http://patchwork.ozlabs.org/series/502601/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2232234/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2232234/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=A5mL4PjE;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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On a\nfaulting user pointer the extable fixup zeros the destination, and the\nfunction writes those zeros to PCI configuration space.\n\nsyzbot triggers this with writev()-ing a NULL iov_base to\n/proc/bus/pci/00/03.0 (the virtio-blk controller in the syzkaller VM):\nzero is written to the Command register, clearing Bus Master Enable,\nand the disk stops responding. In-flight journal writes never complete\nand jbd2 hangs in wait_on_buffer() indefinitely:\n\n INFO: task jbd2/sda1-8 blocked in I/O wait for more than 143 seconds.\n __wait_on_buffer fs/buffer.c:123\n jbd2_journal_commit_transaction+0x388a/0x6870 fs/jbd2/commit.c:837\n kjournald2 fs/jbd2/journal.c:201\n\nproc_bus_pci_read() has the symmetric problem with __put_user(): a\nfaulting user pointer silently drops config-space data and returns\nsuccess.\n\nSwitch both functions to get_user()/put_user(), which combine the\naccess_ok() check with the load/store and return -EFAULT on failure.\nThe up-front access_ok() can be removed accordingly. On error, jump to\na common label that releases the runtime-PM reference and returns\n-EFAULT.\n\nReported-by: syzbot+c7604c9fdd7580cca4e0@syzkaller.appspotmail.com\nCloses: https://syzkaller.appspot.com/bug?extid=c7604c9fdd7580cca4e0\nTested-by: syzbot+c7604c9fdd7580cca4e0@syzkaller.appspotmail.com\nSigned-off-by: Deepanshu Kartikey \n---\nChanges in v2:\n - Use get_user()/put_user() and drop access_ok() (Krzysztof)\n - Rename label to err: per kernel convention (Krzysztof)\n - Simplify error path to release runtime-PM and return -EFAULT (Krzysztof)\n - Apply the same fix to proc_bus_pci_read() (Krzysztof)\n---\n drivers/pci/proc.c | 44 ++++++++++++++++++++++++++++----------------\n 1 file changed, 28 insertions(+), 16 deletions(-)","diff":"diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c\nindex ce36e35681e8..8e624d829840 100644\n--- a/drivers/pci/proc.c\n+++ b/drivers/pci/proc.c\n@@ -53,15 +53,13 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,\n \t\tnbytes = size - pos;\n \tcnt = nbytes;\n \n-\tif (!access_ok(buf, cnt))\n-\t\treturn -EINVAL;\n-\n \tpci_config_pm_runtime_get(dev);\n \n \tif ((pos & 1) && cnt) {\n \t\tunsigned char val;\n \t\tpci_user_read_config_byte(dev, pos, &val);\n-\t\t__put_user(val, buf);\n+\t\tif (put_user(val, buf))\n+\t\t\tgoto err;\n \t\tbuf++;\n \t\tpos++;\n \t\tcnt--;\n@@ -70,7 +68,8 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,\n \tif ((pos & 3) && cnt > 2) {\n \t\tunsigned short val;\n \t\tpci_user_read_config_word(dev, pos, &val);\n-\t\t__put_user(cpu_to_le16(val), (__le16 __user *) buf);\n+\t\tif (put_user(cpu_to_le16(val), (__le16 __user *) buf))\n+\t\t\tgoto err;\n \t\tbuf += 2;\n \t\tpos += 2;\n \t\tcnt -= 2;\n@@ -79,7 +78,8 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,\n \twhile (cnt >= 4) {\n \t\tunsigned int val;\n \t\tpci_user_read_config_dword(dev, pos, &val);\n-\t\t__put_user(cpu_to_le32(val), (__le32 __user *) buf);\n+\t\tif (put_user(cpu_to_le32(val), (__le32 __user *) buf))\n+\t\t\tgoto err;\n \t\tbuf += 4;\n \t\tpos += 4;\n \t\tcnt -= 4;\n@@ -89,7 +89,8 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,\n \tif (cnt >= 2) {\n \t\tunsigned short val;\n \t\tpci_user_read_config_word(dev, pos, &val);\n-\t\t__put_user(cpu_to_le16(val), (__le16 __user *) buf);\n+\t\tif (put_user(cpu_to_le16(val), (__le16 __user *) buf))\n+\t\t\tgoto err;\n \t\tbuf += 2;\n \t\tpos += 2;\n \t\tcnt -= 2;\n@@ -98,7 +99,8 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,\n \tif (cnt) {\n \t\tunsigned char val;\n \t\tpci_user_read_config_byte(dev, pos, &val);\n-\t\t__put_user(val, buf);\n+\t\tif (put_user(val, buf))\n+\t\t\tgoto err;\n \t\tpos++;\n \t}\n \n@@ -106,6 +108,10 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,\n \n \t*ppos = pos;\n \treturn nbytes;\n+\n+err:\n+\tpci_config_pm_runtime_put(dev);\n+\treturn -EFAULT;\n }\n \n static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,\n@@ -129,14 +135,12 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,\n \t\tnbytes = size - pos;\n \tcnt = nbytes;\n \n-\tif (!access_ok(buf, cnt))\n-\t\treturn -EINVAL;\n-\n \tpci_config_pm_runtime_get(dev);\n \n \tif ((pos & 1) && cnt) {\n \t\tunsigned char val;\n-\t\t__get_user(val, buf);\n+\t\tif (get_user(val, buf))\n+\t\t\tgoto err;\n \t\tpci_user_write_config_byte(dev, pos, val);\n \t\tbuf++;\n \t\tpos++;\n@@ -145,7 +149,8 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,\n \n \tif ((pos & 3) && cnt > 2) {\n \t\t__le16 val;\n-\t\t__get_user(val, (__le16 __user *) buf);\n+\t\tif (get_user(val, (__le16 __user *) buf))\n+\t\t\tgoto err;\n \t\tpci_user_write_config_word(dev, pos, le16_to_cpu(val));\n \t\tbuf += 2;\n \t\tpos += 2;\n@@ -154,7 +159,8 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,\n \n \twhile (cnt >= 4) {\n \t\t__le32 val;\n-\t\t__get_user(val, (__le32 __user *) buf);\n+\t\tif (get_user(val, (__le32 __user *) buf))\n+\t\t\tgoto err;\n \t\tpci_user_write_config_dword(dev, pos, le32_to_cpu(val));\n \t\tbuf += 4;\n \t\tpos += 4;\n@@ -163,7 +169,8 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,\n \n \tif (cnt >= 2) {\n \t\t__le16 val;\n-\t\t__get_user(val, (__le16 __user *) buf);\n+\t\tif (get_user(val, (__le16 __user *) buf))\n+\t\t\tgoto err;\n \t\tpci_user_write_config_word(dev, pos, le16_to_cpu(val));\n \t\tbuf += 2;\n \t\tpos += 2;\n@@ -172,7 +179,8 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,\n \n \tif (cnt) {\n \t\tunsigned char val;\n-\t\t__get_user(val, buf);\n+\t\tif (get_user(val, buf))\n+\t\t\tgoto err;\n \t\tpci_user_write_config_byte(dev, pos, val);\n \t\tpos++;\n \t}\n@@ -182,6 +190,10 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,\n \t*ppos = pos;\n \ti_size_write(ino, dev->cfg_size);\n \treturn nbytes;\n+\n+err:\n+\tpci_config_pm_runtime_put(dev);\n+\treturn -EFAULT;\n }\n \n #ifdef HAVE_PCI_MMAP\n","prefixes":["v2"]}