From: Daniella Lee <daniellalee111@gmail.com>
To: mst@redhat.com, marcel.apfelbaum@gmail.com, qemu-devel@nongnu.org
Cc: Daniella Lee <daniellalee111@gmail.com>
Subject: [PATCH] Fix bad overflow check in hw/pci/pcie.c
Date: Fri, 26 Nov 2021 14:13:24 +0800 [thread overview]
Message-ID: <20211126061324.47331-1-daniellalee111@gmail.com> (raw)
Orginal qemu commit hash:14d02cfbe4adaeebe7cb833a8cc71191352cf03b
In function pcie_add_capability, an assert contains the
"offset < offset + size" expression.
Both variable offset and variable size are uint16_t,
the comparison is always true due to type promotion.
The next expression may be the same.
It might be like this:
Thread 1 "qemu-system-x86" hit Breakpoint 1, pcie_add_capability (
dev=0x555557ce5f10, cap_id=1, cap_ver=2 '\002', offset=256, size=72)
at ../hw/pci/pcie.c:930
930 {
(gdb) n
931 assert(offset >= PCI_CONFIG_SPACE_SIZE);
(gdb) n
932 assert(offset < offset + size);
(gdb) p offset
$1 = 256
(gdb) p offset < offset + size
$2 = 1
(gdb) set offset=65533
(gdb) p offset < offset + size
$3 = 1
(gdb) p offset < (uint16_t)(offset + size)
$4 = 0
Signed-off-by: Daniella Lee <daniellalee111@gmail.com>
---
hw/pci/pcie.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index c5ed266337..d7d73a31e4 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -929,8 +929,8 @@ void pcie_add_capability(PCIDevice *dev,
uint16_t offset, uint16_t size)
{
assert(offset >= PCI_CONFIG_SPACE_SIZE);
- assert(offset < offset + size);
- assert(offset + size <= PCIE_CONFIG_SPACE_SIZE);
+ assert(offset < (uint16_t)(offset + size));
+ assert((uint16_t)(offset + size) <= PCIE_CONFIG_SPACE_SIZE);
assert(size >= 8);
assert(pci_is_express(dev));
--
2.27.0
reply other threads:[~2021-11-26 6:15 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211126061324.47331-1-daniellalee111@gmail.com \
--to=daniellalee111@gmail.com \
--cc=marcel.apfelbaum@gmail.com \
--cc=mst@redhat.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.