6.17-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Weißschuh thomas.weissschuh@linutronix.de
[ Upstream commit d1ff0e2d13d6ac3a15be7870e15216726b0a809a ]
dup2() allows both 'old' and 'new' to have the same value, which dup3() does not. If libc dup2() is implemented through the dup3() system call, then it would incorrectly fail in this case.
Avoid the error by handling old == new explicitly.
Fixes: 30ca20517ac1 ("tools headers: Move the nolibc header from rcutorture to tools/include/nolibc/") Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Acked-by: Willy Tarreau w@1wt.eu Link: https://lore.kernel.org/r/20250820-nolibc-dup2-einval-v2-1-807185a45c56@linu... Signed-off-by: Thomas Weißschuh linux@weissschuh.net Signed-off-by: Sasha Levin sashal@kernel.org --- tools/include/nolibc/sys.h | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h index 295e71d34abad..90aadad31f6cb 100644 --- a/tools/include/nolibc/sys.h +++ b/tools/include/nolibc/sys.h @@ -238,6 +238,19 @@ static __attribute__((unused)) int sys_dup2(int old, int new) { #if defined(__NR_dup3) + int ret, nr_fcntl; + +#ifdef __NR_fcntl64 + nr_fcntl = __NR_fcntl64; +#else + nr_fcntl = __NR_fcntl; +#endif + + if (old == new) { + ret = my_syscall2(nr_fcntl, old, F_GETFD); + return ret < 0 ? ret : old; + } + return my_syscall3(__NR_dup3, old, new, 0); #elif defined(__NR_dup2) return my_syscall2(__NR_dup2, old, new);