From 970a3e6745d27f7a1fab9e27e82553a7545aef66 Mon Sep 17 00:00:00 2001 From: "Dylan M. Taylor" Date: Tue, 3 Nov 2026 04:22:36 +0000 Subject: [PATCH] fix(engine): check the opened file, not the looked-up path, before reading it read_capped checked the path's metadata (type and size) and then opened the path again, so an entry swapped between the two steps was read without those checks. The opened handle's metadata is checked as well; the path check stays, so a pipe is still refused before it is opened. --- crates/engine/src/automation/file_access.rs | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/crates/engine/src/automation/file_access.rs b/crates/engine/src/automation/file_access.rs index b40a92f79..26f15700b 100644 --- a/crates/engine/src/automation/file_access.rs +++ b/crates/engine/src/automation/file_access.rs @@ -277,6 +277,14 @@ pub fn read_capped(path: impl AsRef, max: u64) -> Result> { return Err(refuse(format!("is {}, more than the {} allowed here", size(meta.len()), size(max)))); } let f = std::fs::File::open(p).map_err(io(path))?; + // What was opened, not what was looked at: the path could have been swapped in between. + let meta = f.metadata().map_err(io(path))?; + if !meta.is_file() { + return Err(refuse("isn't a regular file (a device or a pipe?), so it isn't read".into())); + } + if meta.len() > max { + return Err(refuse(format!("is {}, more than the {} allowed here", size(meta.len()), size(max)))); + } let mut bytes = Vec::with_capacity(usize::try_from(meta.len()).unwrap_or(0)); f.take(max.saturating_add(1)).read_to_end(&mut bytes).map_err(io(path))?; // It grew after it was looked at.