From 6f0dbf2c44bac406f676cdd9c7f36cc24751b116 Mon Sep 17 00:00:00 2001
From: Nazarii Hnydyn <nazariig@nvidia.com>
Date: Mon, 12 Apr 2021 20:48:44 +0300
Subject: [PATCH] [installer]: Prevent filesystem corruption (#7264)

This improvement reads current SONiC version directly from `/proc/cmdline`.
it supports `grub/aboot/uboot` bootloaders.

**Code snippet**:
```bash
cat /proc/cmdline | sed -n 's/^.*loop=\/*image-\(\S\+\)\/.*$/\1/p'
```

**Description**:
```
-n         don't print lines
s          substitute
^.*        matches anything before the <image_version>
loop=      matches <loop> kernel parameter
\/*image-  matches <image_version> prefix
\(\S\+\)   matches <image_version> group and assigns it to \1
\/.*$      matches anything after the <image_version>
\1         replace everything with <image_version>
p          print it
```
closes #6267

#### Why I did it
* To fix #6267

#### How I did it
* Fixed installer scripts

#### How to verify it
1. Write invalid SONiC version to sonic_version.yml
2. Run SONiC-To-SONiC update
---
 installer/arm64/install.sh  | 8 +++++++-
 installer/armhf/install.sh  | 8 +++++++-
 installer/x86_64/install.sh | 8 +++++++-
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/installer/arm64/install.sh b/installer/arm64/install.sh
index 280d9f200af9..c1e20b62bf42 100755
--- a/installer/arm64/install.sh
+++ b/installer/arm64/install.sh
@@ -98,7 +98,13 @@ if [ "$install_env" = "onie" ]; then
     mount_partition
 elif [ "$install_env" = "sonic" ]; then
     demo_mnt="/host"
-    eval running_sonic_revision=$(cat /etc/sonic/sonic_version.yml | grep build_version | cut -f2 -d" ")
+    # Get current SONiC image (grub/aboot/uboot)
+    eval running_sonic_revision="$(cat /proc/cmdline | sed -n 's/^.*loop=\/*image-\(\S\+\)\/.*$/\1/p')"
+    # Verify SONiC image exists
+    if [ ! -d "$demo_mnt/image-$running_sonic_revision" ]; then
+        echo "ERROR: SONiC installation is corrupted: path $demo_mnt/image-$running_sonic_revision doesn't exist"
+        exit 1
+    fi
     # Prevent installing existing SONiC if it is running
     if [ "$image_dir" = "image-$running_sonic_revision" ]; then
         echo "Not installing SONiC version $running_sonic_revision, as current running SONiC has the same version"
diff --git a/installer/armhf/install.sh b/installer/armhf/install.sh
index 53f2fdf99661..c85170ff256e 100755
--- a/installer/armhf/install.sh
+++ b/installer/armhf/install.sh
@@ -98,7 +98,13 @@ if [ "$install_env" = "onie" ]; then
     mount_partition
 elif [ "$install_env" = "sonic" ]; then
     demo_mnt="/host"
-    eval running_sonic_revision=$(cat /etc/sonic/sonic_version.yml | grep build_version | cut -f2 -d" ")
+    # Get current SONiC image (grub/aboot/uboot)
+    eval running_sonic_revision="$(cat /proc/cmdline | sed -n 's/^.*loop=\/*image-\(\S\+\)\/.*$/\1/p')"
+    # Verify SONiC image exists
+    if [ ! -d "$demo_mnt/image-$running_sonic_revision" ]; then
+        echo "ERROR: SONiC installation is corrupted: path $demo_mnt/image-$running_sonic_revision doesn't exist"
+        exit 1
+    fi
     # Prevent installing existing SONiC if it is running
     if [ "$image_dir" = "image-$running_sonic_revision" ]; then
         echo "Not installing SONiC version $running_sonic_revision, as current running SONiC has the same version"
diff --git a/installer/x86_64/install.sh b/installer/x86_64/install.sh
index 7c0d311b1a8a..d40dedc9a160 100755
--- a/installer/x86_64/install.sh
+++ b/installer/x86_64/install.sh
@@ -467,7 +467,13 @@ if [ "$install_env" = "onie" ]; then
 
 elif [ "$install_env" = "sonic" ]; then
     demo_mnt="/host"
-    eval running_sonic_revision=$(cat /etc/sonic/sonic_version.yml | grep build_version | cut -f2 -d" ")
+    # Get current SONiC image (grub/aboot/uboot)
+    eval running_sonic_revision="$(cat /proc/cmdline | sed -n 's/^.*loop=\/*image-\(\S\+\)\/.*$/\1/p')"
+    # Verify SONiC image exists
+    if [ ! -d "$demo_mnt/image-$running_sonic_revision" ]; then
+        echo "ERROR: SONiC installation is corrupted: path $demo_mnt/image-$running_sonic_revision doesn't exist"
+        exit 1
+    fi
     # Prevent installing existing SONiC if it is running
     if [ "$image_dir" = "image-$running_sonic_revision" ]; then
         echo "Not installing SONiC version $running_sonic_revision, as current running SONiC has the same version"