6.17-stable review patch. If anyone has any objections, please let me know.
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From: Zilin Guan zilin@seu.edu.cn
[ Upstream commit 90f601b497d76f40fa66795c3ecf625b6aced9fd ]
bm_register_write() opens an executable file using open_exec(), which internally calls do_open_execat() and denies write access on the file to avoid modification while it is being executed.
However, when an error occurs, bm_register_write() closes the file using filp_close() directly. This does not restore the write permission, which may cause subsequent write operations on the same file to fail.
Fix this by calling exe_file_allow_write_access() before filp_close() to restore the write permission properly.
Fixes: e7850f4d844e ("binfmt_misc: fix possible deadlock in bm_register_write") Signed-off-by: Zilin Guan zilin@seu.edu.cn Link: https://patch.msgid.link/20251105022923.1813587-1-zilin@seu.edu.cn Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/binfmt_misc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c index a839f960cd4a0..a8b1d79e4af07 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -837,8 +837,10 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer, inode_unlock(d_inode(root));
if (err) { - if (f) + if (f) { + exe_file_allow_write_access(f); filp_close(f, NULL); + } kfree(e); return err; }