ghsa-22ff-fvm7-6wj7
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
gfs2: Check sb_bsize_shift after reading superblock
Fuzzers like to scribble over sb_bsize_shift but in reality it's very unlikely that this field would be corrupted on its own. Nevertheless it should be checked to avoid the possibility of messy mount errors due to bad calculations. It's always a fixed value based on the block size so we can just check that it's the expected value.
Tested with:
mkfs.gfs2 -O -p lock_nolock /dev/vdb
for i in 0 -1 64 65 32 33; do
gfs2_edit -p sb field sb_bsize_shift $i /dev/vdb
mount /dev/vdb /mnt/test && umount /mnt/test
done
Before this patch we get a withdraw after
[ 76.413681] gfs2: fsid=loop0.0: fatal: invalid metadata block [ 76.413681] bh = 19 (type: exp=5, found=4) [ 76.413681] function = gfs2_meta_buffer, file = fs/gfs2/meta_io.c, line = 492
and with UBSAN configured we also get complaints like
[ 76.373395] UBSAN: shift-out-of-bounds in fs/gfs2/ops_fstype.c:295:19 [ 76.373815] shift exponent 4294967287 is too large for 64-bit type 'long unsigned int'
After the patch, these complaints don't appear, mount fails immediately and we get an explanation in dmesg.
{
"affected": [],
"aliases": [
"CVE-2022-49769"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-01T15:15:59Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: Check sb_bsize_shift after reading superblock\n\nFuzzers like to scribble over sb_bsize_shift but in reality it\u0027s very\nunlikely that this field would be corrupted on its own. Nevertheless it\nshould be checked to avoid the possibility of messy mount errors due to\nbad calculations. It\u0027s always a fixed value based on the block size so\nwe can just check that it\u0027s the expected value.\n\nTested with:\n\n mkfs.gfs2 -O -p lock_nolock /dev/vdb\n for i in 0 -1 64 65 32 33; do\n gfs2_edit -p sb field sb_bsize_shift $i /dev/vdb\n mount /dev/vdb /mnt/test \u0026\u0026 umount /mnt/test\n done\n\nBefore this patch we get a withdraw after\n\n[ 76.413681] gfs2: fsid=loop0.0: fatal: invalid metadata block\n[ 76.413681] bh = 19 (type: exp=5, found=4)\n[ 76.413681] function = gfs2_meta_buffer, file = fs/gfs2/meta_io.c, line = 492\n\nand with UBSAN configured we also get complaints like\n\n[ 76.373395] UBSAN: shift-out-of-bounds in fs/gfs2/ops_fstype.c:295:19\n[ 76.373815] shift exponent 4294967287 is too large for 64-bit type \u0027long unsigned int\u0027\n\nAfter the patch, these complaints don\u0027t appear, mount fails immediately\nand we get an explanation in dmesg.",
"id": "GHSA-22ff-fvm7-6wj7",
"modified": "2025-05-01T15:31:46Z",
"published": "2025-05-01T15:31:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49769"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/15c83fa0fd659dd9fbdc940a560b61236e876a80"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/16670534c7cff1acd918a6a5ec751b14e7436b76"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1ad197097343568066a8ffaa27ee7d0ae6d9f476"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/28275a7c84d21c55ab3282d897f284d8d527173c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5fa30be7ba81191b0a0c7239a89befc0c94286d5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/670f8ce56dd0632dc29a0322e188cc73ce3c6b92"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8b6534c9ae9dba5489703a19d8ba6c8f2cfa33c2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d6b1e8ea6f3418c3b461ad5a35cdc93c996b2c87"
}
],
"schema_version": "1.4.0",
"severity": []
}
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- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
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- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.