Jeff King <peff@xxxxxxxx> writes: > I do not mind if consolidation waits for later, but I guess the > immediate question is whether we'd prefer to reduce the limit set by my > patch to a more security-conservative value. It would be easy to swap > out INT_MAX for a 100MB #define on top. > > Maybe this? Sounds sensible. Thanks. > -- >8 -- > Subject: [PATCH] dir.c: reduce max pattern file size to 100MB > > In a2bc523e1e (dir.c: skip .gitignore, etc larger than INT_MAX, > 2024-05-31) we put capped the size of some files whose parsing code and > data structures used ints. Setting the limit to INT_MAX was a natural > spot, since we know the parsing code would misbehave above that. > > But it also leaves the possibility of overflow errors when we multiply > that limit to allocate memory. For instance, a file consisting only of > "a\na\n..." could have INT_MAX/2 entries. Allocating an array of > pointers for each would need INT_MAX*4 bytes on a 64-bit system, enough > to overflow a 32-bit int. > > So let's give ourselves a bit more safety margin by giving a much > smaller limit. The size 100MB is somewhat arbitrary, but is based on the > similar value for attribute files added by 3c50032ff5 (attr: ignore > overly large gitattributes files, 2022-12-01). > > There's no particular reason these have to be the same, but the idea is > that they are in the ballpark of "so huge that nobody would care, but > small enough to avoid malicious overflow". So lacking a better guess, it > makes sense to use the same value. The implementation here doesn't share > the same constant, but we could change that later (or even give it a > runtime config knob, though nobody has complained yet about the > attribute limit). > > And likewise, let's add a few tests that exercise the limits, based on > the attr ones. In this case, though, we never read .gitignore from the > index; the blob code is exercised only for sparse filters. So we'll > trigger it that way. > > Signed-off-by: Jeff King <peff@xxxxxxxx> > --- > dir.c | 10 ++++++++-- > t/t0008-ignores.sh | 8 ++++++++ > t/t6112-rev-list-filters-objects.sh | 12 ++++++++++++ > 3 files changed, 28 insertions(+), 2 deletions(-) > > diff --git a/dir.c b/dir.c > index 914060edfd..ad2b7ebe2d 100644 > --- a/dir.c > +++ b/dir.c > @@ -32,6 +32,12 @@ > #include "tree.h" > #include "hex.h" > > + /* > + * The maximum size of a pattern/exclude file. If the file exceeds this size > + * we will ignore it. > + */ > +#define PATTERN_MAX_FILE_SIZE (100 * 1024 * 1024) > + > /* > * Tells read_directory_recursive how a file or directory should be treated. > * Values are ordered by significance, e.g. if a directory contains both > @@ -1149,7 +1155,7 @@ static int add_patterns(const char *fname, const char *base, int baselen, > } > } > > - if (size > INT_MAX) { > + if (size > PATTERN_MAX_FILE_SIZE) { > warning("ignoring excessively large pattern file: %s", fname); > free(buf); > return -1; > @@ -1211,7 +1217,7 @@ int add_patterns_from_blob_to_list( > if (r != 1) > return r; > > - if (size > INT_MAX) { > + if (size > PATTERN_MAX_FILE_SIZE) { > warning("ignoring excessively large pattern blob: %s", > oid_to_hex(oid)); > free(buf); > diff --git a/t/t0008-ignores.sh b/t/t0008-ignores.sh > index 361446b2f4..02a18d4fdb 100755 > --- a/t/t0008-ignores.sh > +++ b/t/t0008-ignores.sh > @@ -945,4 +945,12 @@ test_expect_success SYMLINKS 'symlinks not respected in-tree' ' > test_grep "unable to access.*gitignore" err > ' > > +test_expect_success EXPENSIVE 'large exclude file ignored in tree' ' > + test_when_finished "rm .gitignore" && > + dd if=/dev/zero of=.gitignore bs=101M count=1 && > + git ls-files -o --exclude-standard 2>err && > + echo "warning: ignoring excessively large pattern file: .gitignore" >expect && > + test_cmp expect err > +' > + > test_done > diff --git a/t/t6112-rev-list-filters-objects.sh b/t/t6112-rev-list-filters-objects.sh > index 43e1afd44c..0387f35a32 100755 > --- a/t/t6112-rev-list-filters-objects.sh > +++ b/t/t6112-rev-list-filters-objects.sh > @@ -701,4 +701,16 @@ test_expect_success 'expand blob limit in protocol' ' > grep "blob:limit=1024" trace > ' > > +test_expect_success EXPENSIVE 'large sparse filter file ignored' ' > + blob=$(dd if=/dev/zero bs=101M count=1 | > + git hash-object -w --stdin) && > + test_must_fail \ > + git rev-list --all --objects --filter=sparse:oid=$blob 2>err && > + cat >expect <<-EOF && > + warning: ignoring excessively large pattern blob: $blob > + fatal: unable to parse sparse filter data in $blob > + EOF > + test_cmp expect err > +' > + > test_done