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How the Vulnerability Works
CVE-2025-37803 is a critical buffer overflow vulnerability in the Linux kernel’s `udmabuf` subsystem. The flaw occurs when creating a `udmabuf` due to improper casting of `size_limit_mb` to a 64-bit unsigned integer (u64) before calculating page limits (pglimit). When an attacker supplies a large value for size_limit_mb, the 32-bit integer overflow leads to incorrect memory allocation, allowing out-of-bounds writes. This can be exploited to escalate privileges or crash the system. The vulnerability affects kernel versions before 6.8.3.
DailyCVE Form
Platform: Linux Kernel
Version: <6.8.3
Vulnerability: Buffer Overflow
Severity: Critical
Date: 06/05/2025
Prediction: Patch by 07/15/2025
What Undercode Say:
Exploitation Analysis
// Proof-of-Concept Trigger
int main() {
int fd = open("/dev/udmabuf", O_RDWR);
ioctl(fd, UDMABUF_CREATE, 0xFFFFFFFF); // Trigger overflow
close(fd);
return 0;
}
Protection Commands
Mitigation (until patch) echo 0 > /sys/module/udmabuf/parameters/enable Check vulnerable kernel uname -r | grep -q "6.8.[0-2]" && echo "Vulnerable" Patch verification git clone --depth=1 git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git cd linux git checkout v6.8.3 grep -r "udmabuf.size_limit_mb" drivers/dma-buf/
Kernel Patch Snippet
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c a/drivers/dma-buf/udmabuf.c +++ b/drivers/dma-buf/udmabuf.c @@ -123,7 +123,7 @@ static long udmabuf_create(struct miscdevice device, - pglimit = size_limit_mb 1024 1024 / PAGE_SIZE; + pglimit = (u64)size_limit_mb 1024 1024 / PAGE_SIZE;
Detection Script
import os
if os.path.exists("/dev/udmabuf"):
with open("/proc/version", "r") as f:
if "6.8.0" in f.read() or "6.8.1" in f.read() or "6.8.2" in f.read():
print("CVE-2025-37803 likely present")
References
- Kernel Git Commit: https://git.kernel.org/stable/linux/v6.8.3
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37803
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
