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Date:   Tue, 26 May 2020 20:52:45 +0200
From:   Greg Kroah-Hartman <>
Cc:     Greg Kroah-Hartman <>,,
        Thiago Macieira <>,
        Al Viro <>,
        Sasha Levin <>,
Subject: [PATCH 4.19 10/81] fix multiplication overflow in copy_fdtable()

From: Al Viro <>

[ Upstream commit 4e89b7210403fa4a8acafe7c602b6212b7af6c3b ]

cpy and set really should be size_t; we won't get an overflow on that,
since sysctl_nr_open can't be set above ~(size_t)0 / sizeof(void *),
so nr that would've managed to overflow size_t on that multiplication
won't get anywhere near copy_fdtable() - we'll fail with EMFILE
before that.

Cc: # v2.6.25+
Fixes: 9cfe015aa424 (get rid of NR_OPEN and introduce a sysctl_nr_open)
Reported-by: Thiago Macieira <>
Signed-off-by: Al Viro <>
Signed-off-by: Sasha Levin <>
 fs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/file.c b/fs/file.c
index 780d29e58847..3762a3f136fd 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -70,7 +70,7 @@ static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt,
 static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
-	unsigned int cpy, set;
+	size_t cpy, set;
 	BUG_ON(nfdt->max_fds < ofdt->max_fds);

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