Commit 5304877936c0 ("NFSD: Fix strncpy() fortify warning") replaced strncpy(,, sizeof(..)) with strlcpy(,, sizeof(..) - 1), but strlcpy() already guaranteed NUL-termination of the destination buffer and subtracting one byte potentially truncated the source string.
The incorrect size was then carried over in commit 72f78ae00a8e ("NFSD: move from strlcpy with unused retval to strscpy") when switching from strlcpy() to strscpy().
Fix this off-by-one error by using the full size of the destination buffer again.
Cc: stable@vger.kernel.org Fixes: 5304877936c0 ("NFSD: Fix strncpy() fortify warning") Signed-off-by: Thorsten Blum thorsten.blum@linux.dev --- fs/nfsd/nfs4proc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index 71b428efcbb5..32be002a248f 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1469,7 +1469,7 @@ static __be32 nfsd4_ssc_setup_dul(struct nfsd_net *nn, char *ipaddr, return 0; } if (work) { - strscpy(work->nsui_ipaddr, ipaddr, sizeof(work->nsui_ipaddr) - 1); + strscpy(work->nsui_ipaddr, ipaddr); refcount_set(&work->nsui_refcnt, 2); work->nsui_busy = true; list_add_tail(&work->nsui_list, &nn->nfsd_ssc_mount_list);
From: Chuck Lever chuck.lever@oracle.com
On Tue, 05 Aug 2025 19:53:02 +0200, Thorsten Blum wrote:
Commit 5304877936c0 ("NFSD: Fix strncpy() fortify warning") replaced strncpy(,, sizeof(..)) with strlcpy(,, sizeof(..) - 1), but strlcpy() already guaranteed NUL-termination of the destination buffer and subtracting one byte potentially truncated the source string.
The incorrect size was then carried over in commit 72f78ae00a8e ("NFSD: move from strlcpy with unused retval to strscpy") when switching from strlcpy() to strscpy().
[...]
Applied to nfsd-testing, thanks!
[1/1] NFSD: Fix destination buffer size in nfsd4_ssc_setup_dul() commit: 5486ae619bff16a8c885afab7f40b10c69030344
-- Chuck Lever
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